这个标志是何含义？（）
A．掉头
B．倒车
C．左转
D．绕行
参考答案：A
Some modern teaching equipment as well as hundreds of computers _______ to ten Hope Schools in
South China．[ ]
A．were sent
B．was sent
C．have sent
D．had been sent
目前常用的冷凝器有三类，是什么？
