---Wow! They look so delicious!---_____.
| A．please help yourself | B．Help yours | C．Yes, they do | D．NO, they don’t |
53. Our music teacher often enjoyed _____ playing the violin in his spare time.
| A．him by | B．himself by | C．him in | D．himself with |
52. The struggle against sand storm will not end _____ victory unless we pay much attention to the balance of nature.
| A．at | B．in | C．for | D．With |
51. Don’t put your cell (手机) _____ the edge of the table, or it will fall off
| A．at | B．on | C．to | D．In |
50. The Englishman has a very good ear _____ music. You can ask him for some advice.
| A．at | B．of | C．for | D．In |
49. He goes _____ at 8 a.m. and comes _____ at 5 p.m. Today he is _____.
| A．on duty; off duty; on night duty | B．on his duty; off the duty; on night duty |
| C．to duty; from duty; at night duty | D．in duty; out duty; at night duty |