5644981精确到万位的近似数的有效数字的个数为[ ]
A.6个
B.4个
C.3个
D.5个
答案:C
Tom, there is________on TV tonight, let’s read books instead.
A.interesting something
B.something interesting
C.interesting nothing
D.nothing interesting
刀具前刀面磨损后,刀具的强度()。
A.降低
B.提升
C.不变
D.二者无联系