大气化学要研究与气候和环境、生态过程密切相关的大气化学气体成分（）、输送、化学转换规律。
A.产生
B.源汇
C.汇集
D.堆积
参考答案：B
At the end of each month when he comes back from school he will be asked by his strict father to ___________ where every cent goes.
A．watch over
B．put forward
C．account for
D．set off
加热炉炉管发生破裂时，炉膛温度上升，炉出口温度下降。
