Chọn từ thich hợp: The Great Wall in China was built / were built / built / build many centuries ago

The Great Wall in China was built / were built / built / build many centuries ago.

I think collector / collecting / collects / collection coins is very interesting.

Ruby was late for class yesterday, and / so / but / or / because she missed the first bus.

The weather is cold today, and / so / but / or / because you should put on a coat. 

He has a toothache, and / so / but / or / because he still eats lots of sweets and cakes.

You should bring an umbrella, and / so / but / or / because you will be wet.

Take up a new hobby, and / so / but / or / because you’ll have some new friends.