20. A text-input interface displaying method, applied to an electronic device having an input device and a display device, wherein the display device has a display region, the display region has a predetermined display area, the text-input interface displaying method comprises: displaying a text input interface on the display region, wherein the text input interface has a first display region and a second display region, the first display region and the second display region each comprising a plurality of display blocks, wherein each of the display blocks is arranged to display a character, wherein the first display region and the second display region are provided for users to do a text editing by the input device, and the text input interface has an interface area; and displaying a first set of characters in the display blocks of the second display region; determining whether the input device receives a number of input signals corresponding to selection of characters of the first set of characters exceeding a predetermined value; when the number of input signals corresponding to selection of characters of the first set of characters exceeds the predetermined value in the text editing, displaying a second set of characters in the display blocks of the first display region, wherein the second set of characters leaves at least one display block empty; and making the at least one empty display block transparent and making the at least one empty display block accumulate at the end of the first display region, thereby dynamically adjusting the interface area of the text input interface to change the ratio of the interface area and the predetermined display area of the display region according to the input signals of the characters that have been selected and an input rule table, wherein the input rule table comprises a variety of combinations of characters that are used for constructing words.
20. A text-input interface displaying method, applied to an electronic device having an input device and a display device, wherein the display device has a display region, the display region has a predetermined display area, the text-input interface displaying method comprises: displaying a text input interface on the display region, wherein the text input interface has a first display region and a second display region, the first display region and the second display region each comprising a plurality of display blocks, wherein each of the display blocks is arranged to display a character, wherein the first display region and the second display region are provided for users to do a text editing by the input device, and the text input interface has an interface area; and displaying a first set of characters in the display blocks of the second display region; determining whether the input device receives a number of input signals corresponding to selection of characters of the first set of characters exceeding a predetermined value; when the number of input signals corresponding to selection of characters of the first set of characters exceeds the predetermined value in the text editing, displaying a second set of characters in the display blocks of the first display region, wherein the second set of characters leaves at least one display block empty; and making the at least one empty display block transparent and making the at least one empty display block accumulate at the end of the first display region, thereby dynamically adjusting the interface area of the text input interface to change the ratio of the interface area and the predetermined display area of the display region according to the input signals of the characters that have been selected and an input rule table, wherein the input rule table comprises a variety of combinations of characters that are used for constructing words. 23. The electronic device as claimed in claim 20 , wherein by default the processing unit enables the first display region to display a space key and a case switching key, and when the number of input signals corresponding to selection of characters of the first set of characters exceeds the predetermined value in the text editing, the processing unit enables the first display region to display the space key, the case switching key and the second set of characters according to the English input rule table and enables the second display region to keep displaying the first set of the English letters.