Doctors had fixed it in place with metal pins .

医生用金属别针将它安了回去。

By an 1889 international accord , the mass of this metal cylinder defines the kilogram .

1889年某项国际协议中规定，该铂铱合金圆柱体的质量为1千克。

Neodymium is a rare earth metal .

钕是一种稀土金属。

Metal detectors are a big worry .

金属探测器是个大麻烦。

Some schools have installed metal detectors .

一些学校则安装了金属探测器。