He is naughty sometimes, but ____ he is a good boy

We would have to put off the visit to the Water Cube________ it rain tomorrow.

Many experts hold the view teacherdevelopment is the key to bettereducation lies

Lily, could you please pass me the ______ I want to cut the apple.—Sure, here you are.

Before a problem can be solved，it must be obvious____the problem itself is.