选哪个？要有讲解

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

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。