【简答题】写出以下单词的过去式1. is2.do3.are4.take5.swim
【单选题】选择出如下图所示的红色线,最快捷的选择方法是
【简答题】John arrived later ______ the baseball because he had to run errands for his mom in the morning to the grocery store and the post office.
【单选题】在改进型积分电路中,输入信号为方波信号时,输出为()
【简答题】John arrived later others. This made his boss angry.