预防甲流要注意什么？
参考答案：
勤洗手、勤开窗通风、锻炼身体、均衡饮食。
They all looked ____ at the master and felt quite _____．
A．sad; sad
B．sadly; sadly
C．sad; sadly
D．sadly; sad
Jack narrowly fell off the cliff, but managed to__________ until help came.
A．keep on
B．hang on
C．live on
D．count on
