椎基底动脉系统短暂性脑缺血发作最常见的症状是：（）
A.眩晕
B.耳鸣和耳聋
C.跌倒发作
D.吞咽困难
E.复视
参考答案：A
The growing speed of a plant is influenced by a number of factors, ______ are beyond our control.
A．most of them
B．most of what
C．most of which
D．most of that
正在运行的进程信号量S上作P操作后，当S<0时，进程将进入信号量的______。
A．等待队列
B．就绪队列
C．后备队列
D．提交队列
