【单选题】He doesn’t know _________ English because he has studied it for only _________ weeks.
【单选题】Though he has studied at English for ten months, he can still _ speak the language. [ ]
【单选题】Robert is away. He _______ America since last week.
D.
has become a manager in
【单选题】下面关于符号对象说法错误的是()
A.
符号对象可以进行“大于”、“大于等于”、“小于”、“小于等于”的运算
【单选题】在电路中测得三极管三个电极的电位如下图所示,此三极管工作在( )。
【单选题】良性黏膜类天疱疮与寻常型天疱疮的共同特征不包括()