It is the America’s selling weapons to Taiwan cast a shadow on the Sino—US relationship

Do you spend a lot of time____ computer—No, but I spend much time_____ doing my homework.

You’d better _______ smoking. It’s bad for your health.

Where is North Korea —It lies ______ the northeast of China.

226. Einstein lived the rest of his life quietly in America and _____ American nationality in 1940.