動詞不定式進行式表示動作正在進行，與謂語動詞表示的動作同時發(fā)生。如：
He see ms to be recovering.他看來在康復。
When he came in，I happened to be lying on the bed，reading. 他進來的時候，我碰巧正躺在床上看書。
[英語語法手冊]非限定動詞 E
動詞不定式的被動語態(tài)
動詞不定式有兩種被動語態(tài)形式：
一般式to be written
完成式to have been written
例：
The next thing to be done is to carry away the earth.下-步要做的事是把土運走。
No harm seems to have been done.似乎并沒有造成損害。
分裂不定式
有時在不定式符號"to"和動詞原形之間插入一個副詞，這種現(xiàn)象叫做分裂不定式(split infinitive)。插入動詞不定式的副詞，習慣上往往與不定式動詞連在一起。如：
He likes to half close his eyes.他喜歡半閉著眼睛。
Our object is to further cement friendly relations between the two countries.我們的目的是進一步加強兩國之間的友好關系。
At first he wasn't interested in bookkeeping，but later he began to actually like it.起初他對會計工作沒有興趣，但到后來倒喜歡起它來了