Metal ______making machines and many other things.

A．used to

B．is used for

C．is used as

D．is used to

下面表达式中，( )的运算结果与其他三个不同。

A．Exp(-3.5)

B．Int(-3.5)+0.5

C．-Abs(-3.5)

D．Sgn(-3.5)-2.5