只有4种: 腺嘌呤 、 胸腺嘧啶 、 鸟嘌呤和胞核嘧啶.There are just four kinds: adenine, thymine, guanine and cytosine.腺嘌呤:在DNA和RNA中发现的含氮的碱基 ( 6 - 氨基嘌呤 ).Adenine A nitrogenous base ( 6 - amino - purine ) found in DNA and RNA.尿嘧啶 -- 核糖核酸中的一种嘧啶,与腺...
Clothes were thrown in the luggage in an untidy heap.衣服被乱糟糟地扔进旅行箱里。They had jumbled it all up into a heap.他们把所有的东西胡乱堆成了一堆。Lee and I fell in a tangled heap.李和我扭作一团，摔倒在地。...
Frances invited them to occupy the upstairs of her home.弗朗西丝邀请他们住在她家的楼上。They huffed and puffed as they carried the sofa upstairs.他们把沙发抬上楼时气喘吁吁。I'll take my coat upstairs. Shall I take yours, Roberta?...我要把我的外套拿到楼上去。...