一个直齿齿条齿厚为3.14mm,则齿条模数为()。
A.4mm
B.3mm
C.2.5mm
D.2mm
参考答案:D
已知函数f(x)=mx2+lnx﹣2x在定义域内不是单调函数,则实数m的取值范围( )
Then came the disturbing news ______ Dolly had become seriously ill.
A.how
B.why
C.whether
D.that