This is a special clock. A team from China made it.

It is the world’s smallest chip atomic (原子的) clock. It is smaller than a finger. It is also very accurate (精确的) — it only goes wrong less than 1 second in 30,000 years.

This tiny clock can help us in many ways. It can work in small satellites up in the sky. It can also help drones (无人机) fly together in groups, or guide machines under the water.

1. 1.This special clock is made by a/an ______ team.

A    Japanese

B    Chinese

C    American

D    English

2. 2.The clock is smaller than a ______.

A    finger

B    book

C    bag

D    desk

3. 3.The clock can guide under the ______.

A    water

B    sky

C    ground

D    grass

4. 4.China’s new clock may ______ how machines work.

A    stop

B    find

C    lose

D    change