________ is mentioned above, the number of the students in senior high schools is increasing.

[　　]

He was very rude to the customs officer, ________ of course made things even worse.

[　　]

I had neither a raincoat nor an umbrella. ________ I got wet through.

[　　]

________ caused the accident is still a complete mystery.

[　　]

He made another wonderful discovery, ________ of great importance to science.

[　　]

I wonder ________ Jenny hasn't written us recently. We should have heard from her by now.

[　　]

The mother didn't know ________ to blame for the broken glass as it happened while she was out.

[　　]

The famous basketball star, ________ tried to make a comeback, attracted a lot of attention.

[　　]

－I think it's going to be a big problem.

－Yes, it could be.

－I wonder ________ we can do about it.

[　　]

－I drove to Zhuhai for the air show last week.

－Is that ________ you had a few days off?

[　　]