网箱养鱼的每次投喂量，应使鱼摄食到什么程度最为理想（）。
A、100％饱
B、70-80％饱
C、50％饱
参考答案：B
I didn't know what ____ to her last night. [ ]
A. was happened
B. happening
C. happened
D. was happen
下列实验仪器不宜直接用来加热的是（ ）
A．试管
B．坩埚
C．蒸发皿
D．烧杯
