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...
她听讲座时一直在打呵欠.She yawned during the lecture.听得见我打呵欠的声音 么 ?Can you hear my yawn?我上他的课时, 总是竭力地制止自己打呵欠.When I attended his lecture, I always tried hard to strangle yawns....
火鸡能重达50磅。Turkeys can reach enormous weights of up to 50 pounds.B-19重达80吨,无疑是世界上最大、最先进的军用飞机。Weighing in at eighty tons, the B-19 was easily the largest and most sophisticated warplane in the world.所有的猪在活重达90公斤左右时宰杀.All th...