take the passive voice. It is formed for any verb tense by appending -s to the tense. For verbs ending in -r, the -r is actually replaced by the -s altogether. Verbs ending in -er often lose the -e- as well, other than in very formal style: ("strengthens") becomes or ("is strengthened"); exceptions are monosyllabic verbs and verbs where the root ends in -s. Swedish uses the passive voice more frequently than English. Conjugating verbs Swedish verbs are divided into four groups: {| class="wikitable" |- ! Group ! Description |- | align="center" | 1 || regular -ar verbs |- | align="center" | 2 || regular -er verbs |- | align="center" | 3 || short verbs, ending in -r|- | align="center" | 4 || strong and irregular verbs, ending in -er or -r|} About 80% of all verbs in Swedish are group 1 verbs, which is the only productive verb group. Swenglish variants of English verbs can be made by adding -a to the end of an English verb, sometimes with minor spelling changes; the verb is then treated as a group 1 verb. Examples of modern loan words within the field are and . Swenglish variants that may be used but are not considered standard Swedish include maila/mejla (, "to email" or "mail") and savea/sejva (, "to save"). The stem of a verb is based on the present tense of the verb. If the present tense ends in -ar, the -r is removed to form the stem, e.g., → kalla-. If the present tense ends in -er, the -er is removed, e.g., → stäng-. For short verbs, the -r is removed from the present tense of the verb, e.g., → sy-. The imperative is the same as the stem. For group 1 verbs, the infinitive is the same as the stem (-a), the present tense ends in -r, the past tense in -de, the supine in -t, and the past participle in -d, -t, and de. For group 2 verbs, the stem ends in a consonant, the infinitive ends in -a, and the present tense in -er. Group 2 verbs are further subdivided into group 2a and 2b, depending on whether the stem ends in a voiced or a voiceless consonant (phonetically the same as English). For group 2a verbs, the past tense ends in -de and the past participle in -d, -t, and -da; e.g. the stem of ("to