有n个电阻均为R的电阻串联，其等效电阻为（）。
参考答案：nR
两栖动物生殖和发育的特点是（ ）
A．体外受精，变态发育
B．体外受精，完全变态发育
C．体内受精，变态发育
D．体内受精，水中变态发育
The terrible drought has captured worldwide attention. As responsible citizens, we must never ______ the terrible situation that our common home is faced with.
A．overlook
B．miss
C．forget
D．overestimate
