你想知道Amy的妈妈 有多大了?你应该怎么说?()
A:How old is your mom?
B:How are you?
C:How old are you?
比一比,再组词。
鲸 ____
掠 ____
看图读一读填空,把句子代码填在正确的横线上。
A. There's a blackboard in it. There are eighteen desks and eighteen chairs in it.
B. There are three books in it. C. There's a ruler. D. There's a big library.
如图为交流发电机的工作原理图,经过0.05s线框从图示位置匀速转过90°.如图所示位置线框中的感应电流____(选填“最大”或“最小”),该发电机产生的 交流电的频率为____.