—______ there is no water left on the earth? —I really don’t know.

I am going to Tian’anmen Square to watch the raising of the national flag with Lin Tao ________ it rains early tomorrow morning.

- Have you known each other for long? - Not very long, _______ we started to work in the company.

 Ms  Wang  is  an  excellentteacher.________ in our class loves her.

----Who will come and_______ if you don’t?----Either my father or my brother will come to the airport.