紫外成像仪常采用的紫外线波长范围在()之间。
A.240nm-280nm
B.0.75μm-1000μm
C.2μm-14μm
D.10nm-400nm
参考答案:A
﹣2的相反数是( ).
The time is not far away______modern communications will become widespread in China’s vast countryside.
A.as
B.until
C.before
D.when