帮忙啊（英语）1. The math problem is too difficult for him to work

帮忙啊（英语）
1. The math problem is too difficult for him to work out .(改为复合句）
The math problem is ____ difficult_____ he____ work it out.
2. The little boy is too short to reach the book on the shelf.(改为同义句)
The little boy ___ ___ ___ to reach the book on the shelf.
3. Why don't you come to the party?(同上)
____ ____ come to the party?