Combine the following simple sentences into complex sentences.

This is the college. I studied here.

Combine the following simple sentences into complex sentences.

It was $10$ o'clock. My father left for office then.

Combine the following simple sentences into complex sentences.

Can you tell me the reason? You are wasting time.

Combine the following simple sentences into complex sentences.

The boy was present there. The teacher gave him a prize.

Combine the following simple sentences into complex sentences.

I bought a pen. I shall give you the same pen.

Combine the following simple sentences into complex sentences.

I was the first man. I heard his name on the radio.

Combine the following simple sentences into complex sentences.

They were sitting under a tree. Its shade was very cool.

Combine the following simple sentences into complex sentences.

I shall go by the Taj Express. It goes to Agra direct.

Combine the following simple sentences into complex sentences.

They are reading a book. It is very rare.