按信号的类型来分类,信道可分为()。
A、模拟信道;
B、频分制信道;
C、时分制信道;
D、数字信道。
参考答案:A, D
Lucy does her homework very ________. She is ________ than Lily.
A.carefully, much more careful
B.carefully, much carefuller
C.careful, many more careful
D.careful, a little carefuler
仪器从仪器箱中取出后应()。
A.盖好仪器箱,立放
B.盖好仪器箱,平放
C.人可以坐在仪器箱上
D.将其他的辅助小工具放入仪器箱中,防止丢失