无溢流堰跳汰机为了控制矸石层厚度,并使矸石不进入中煤段,可使()的筛板比()的筛板高点。
参考答案:中煤段;矸石段
Thanks to scientific research, we now have a good understanding of ______ an earthquake is and why it happens.
A.how
B.which
C.whether
D.what
在太阳光照射下,一个高为3米的竹杆其影子长为米,则一个半径为1米的球其影子最长为:()
A.
B.
C.
D.