另两个为胸腺嘧啶和胞嘧啶, 即称为嘧啶的单环结构.The other two, thymine and cytosine, are single ring structures called pyrimidines.直到不久以前,人们对胸腺的功能尚不明了.The function of the thymus was unknown until relatively recently.动物的免疫系统由两个主要部分组成,即胸腺和骨髓系统.I...
Landlords can charge a returnable deposit.房东可以收取一笔可退还的押金。Some landlords and landladies are racially prejudiced.一些房东有种族偏见。Paying rent simply helps to line the pockets of landlords. It's far better to put your money i...
是低温使水变成冰的 吗 ?Is it the low temperature that turns the water to ice?这是雪和冰的结晶体.It is snow and ice crystals.覆盖着冰的路面对驾驶汽车的人是个危险的隐患.Icy roads are a hidden danger to motorists....
Hypoid gear transmission is the most complicated transmission. The parameters of ma - chinking are hard to cakulate.准双曲面齿轮是齿轮传动中最复杂的, 其工艺锥参数和加工调整计算都涉及两个相错圆锥的相切接触条件.Fixtures are generally mechanical devices used to assist...