We tried _____ both the front door and the back door, but no one answered.
A. knocking at B. to knock at
C. knock on D. knocking
參考答案:A
try to do尽量，努力做某事 try to finish it 尽量完成它 try doing sth 试着做某事 尝试做 后面跟动名词或名词 try （using ）this one 试试用这个
TRY
1. 试图;努力[+to-v]
We'll try to improve our teaching methods.
我们要设法改进教学方法。
2. 尝试,试行[+v-ing]
Let's try knocking at the back door.
咱们敲后边的门试试。
