IPeople failed to solve the problem 怎莫改被动
help to solve the problem?
---would you solve the problem if this method failed?
The problem is easy to solve.为什么用to solve
The________designed some programs to solve the problem.
He____________a good idea to solve the problem.
The problem is ___ to solve.
He_________a good idea to solve the problem.
we found this problem difficult to solve solve为什么不用被动
solve the problem
the key to solve the problem is to _____ trees
The way(referred to to solve)the problem sounds reasonable.
To solve the energy problem这里to表示什么