Is this grammar correct? (span of time)


一週間後に行く means : We arrive there in a week.  
日本語は九ヶ月間勉強している means : I've been studying Japanese for 9 months.  
ニ日間に休む means : absent for 2 days.




~~一週間後に行く means "we'll go there after a week".

"We arrive there in a week" should be 一週間の内{うち}に / 一週間以内に / 一週間で 着く.~~

"I've been studying Japanese for 9 months" for 日本語は九ヶ月間勉強している is correct.

ニ日間に休む means "I'll take a break sometime within a certain two days".

"Absent for 2 days" should be 二日間 いない / 休む




~~一週間後に行く means "we'll go there after a week".

"We arrive there in a week" should be 一週間の内{うち}に / 一週間以内に / 一週間で 着く.~~

"I've been studying Japanese for 9 months" for 日本語は九ヶ月間勉強している is correct.

ニ日間に休む means "I'll take a break sometime within a certain two days".

"Absent for 2 days" should be 二日間 いない / 休む

