The English teacher isn't here. She ________ to the office.
A:has been
B:has gone
C:went
D:did go
读山区(林区)与平原(水稻产区)商业网点示意图,并回答下列问题:
某品牌的微型电脑吸尘器有两个开关,开关S1控制照明灯L和吸尘电动机M,开关S2只控制吸尘电动机M。下列电路图符合要求的是( )