1. about

2. of

3. in

4. at

1. He is weak but is a hard worker.

2. He is weak and hard worker.

3. In spite of being weak, he works hard.

4. Though he is weak, he works hard.

1. see exhaustively

2. eyes of birds

3. a view of the sky

4. a rough idea

1. By whom will you be helped?

2. By whom would you be helped?

3. By whom you would be helped?

4. By whom you will be helped?

1. This is his speaking.

2. This is himself speaking. This is him speaking.

3. This is he speaking.