在静止的空气中,直径在1~100微米的粉尘颗粒作()沉降。
参考答案:等速
----Alice,turn off the light and lock the door before you leave.
----- ____________.[ ]
A. Got it
B. Made it
C. Heard it
D. Taken it
一般加热炉用煤气烧嘴分为()和调焰烧嘴。