1. Choose the correct form of the Gerund:
1. He insists on the problem (solving, being solved) at once.
2. The teacher was surprised at the students (not knowing, not being known) this theorem.
3. He relied on his paper (discussion, discussed) tomorrow.
4. Did you find any difficulty in (being solved, solving) this problem?
5. The sportsman was proud of (having awarded, having been awarded) the prize.
6. We heard of the experiment (having started, having been started) last weak.
7. I remember his (having interested, having been interested) in languages in his childhood.