题型:问答题 — Listen! Someone is singing in the music room. It ______ be Jim. He practices singing there every day. — It ______ be him. He has gone to Beijing. [ ]A. can; can't B. must; may notC. must; can't D. may; may not 查看答案
题型:问答题 设单片机的fosc=6MHz,下面程序是100ms延时的子程序。 DELAY: MOV R7,#64H A0: MOV R6,#0FAH DJNZ R6,$ DJNZ R7.DELAY RET 错误:______ 改正:______ 查看答案