Li Ming's plane arrived ____________ 4: 55.[ ]
A. in
B. on
C. at
答案：C
It was about 600 years ago __________ the first clock was made.
A．that
B．until
C．before
D．when
已知标准器检定证书注明：66.65mm刻度处容量为20.00L，计量颈分度容量V颈＝1.95mL/mm。对加油机进行自校，其数据如下，试判断该加油机本次自校是否合格。（不考虑温度的影响）
