Answer:
1. Over
2. With
Explanation:
The question is incomplete, but it is quite clear that what the question wants are words that completes the given sentences.
Therefore, the words that complete the given sentences are "over" and "with* and the complete sentence after adding those words will be:
1. He says he's turned OVER a new leaf, but I have my doubts.
2. The boss needs an assistant WITH good knowledge of foreign trade.
