但要注意和以下结构进行区别：
take the trouble to do sth.
trouble to do sth.
have (no) time to do sth.
例句
a. I worked so late in the office last night that I hardly had time______the last bus.
A.to have caught
B.to catch
C.catching
D.having caught
正确答案：B。
b. — How do you find your new apartment?
— Well, it’s quite nice really, although I have a hard time getting used to living in a big place.
（2）表示“情不自禁……，不得不……”的短语
can’t help doing
can’t resist doing
can’t keep from doing
can’t hold back from doing
can’t keep back from doing
例：No one can help liking Tom; he is such a cute boy.
但要注意下列短语要接不定式：
can’t help but do
can’t choose but to do
（3）主动形式表示被动含义：be worth doing “值得做……”
相当于be worthy ofbeing done或be worthy to be done。
a. The book is worth reading.
b. The book is worthy of being read.
c. The book is worthy to be read.