When you stand on the top of the mountain and overlook the surrounding scenery, you will find it is ______ to climb it up with effort.
34 He tried his best to solve the problem, _______ difficult it was.
33. The oil in the cooker ___ heavy smoke, which made us in tears and difficult to open our eyes .
32. ---I can’t see words on the blackboard clearly . ---Why, your eyes need _____ .Perhaps you need ______ glasses .
31. Attention must be paid to ______ science and technology..
30. When I first set _____ in Germany, I had no idea what the future may have ____ for me.