按拉户降示的古兰经当中第一次降示的是那一章？最后降示的是那一章？

Having checked the doors were closed, and ___ all the lights were off, the boy opened the door to his bedroom.

A．why

B．that

C．when

D．ours

下列物质属于纯净物的是

A．葡萄糖

B．聚乙烯

C．医用酒精

D．油脂

在数控机床编程中，为了编程方便，一律规定刀具固定，工件移动。

在冻害处所，横垫板重复使用不得超过（）块，较厚的垫板应放在下层。

A.2

B.3

C.4

D.1

简述物流信息化对物流业的影响。