炉内气流经过二次分布。
参考答案:错
Let those in need ________ that we will go all out to help them. (2013·陕西,13)
A.to understand
B.understand
C.understanding
D.understood
如图标志的含义是什么()
A.禁止掉头
B.禁止左转弯
C.准许掉头
D.准许左转弯