The color green ________ spring, which is the time of year when things in nature start to grow after a long winter.
35. Do you know who ________ using water in this way?
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..