南美洲________

There is ________（有人）knocking at the door. Please go and see.

His father often takes a ________（笔记本电脑）with him on business.

The mouse is used for ________（指向）to things on the screen and choosing them.

Before the printing press, people wrote books ________（靠手写）.

看!你的便携式计算机正放在他的腿上。

哪一个更重要，印刷机还是电脑?

________ is ________ ________，a printing press or computer?