一人以每分钟60米的速度沿铁路步行,一列长144米的客车对面开来,从他身边通过用了8秒钟,列车的速度是____ 米/秒.
在下列分子中,有的是构成生物体的氨基酸,有的不是.请认真分析后回答:
①细胞内液 ②血浆 ③淋巴 ④组织液 ⑤消化液.
As we know, his father is a very famous scientist in physics. But what you don't know is that he _______ as a farmer for five years.