【简答题】质粒运载体用EcoRI切割后产生的片段如下: AATTC......G G......CTTAA 为使运载体与目的基因相连,含有目的基因的DNA除可用EcoRI切割外,还可用另一种限制性内切酶切割,该酶必须具有的特点是___________________。
【简答题】I shall never forget the day when the earthquake took place. The time was about 5 o’clock in the afternoon and I was driving along the road to take my daughter from school. Our plan was to go swimming...
【单选题】瘦肉精是一类对人体健康危害极大的化学物质,政府已严禁在猪饲料中添加瘦肉精.常见的瘦肉精化学式为C 12 H 18 OCl 2 N 2 ,下列有关这种瘦肉精的说法中正确的是( )
B.
分子中碳、氢、氧三种元素的质量比为72:9:8
D.
由C 12 H 18 O、Cl 2 、N 2 三种分子组成
【多选题】下列就信用证与贸易合同的相互关系进行了表述,其中正确的是( )。
【单选题】阅读本文完成单项选择21--25题 I shall never forget the day when the earthquake took place. The time was about 5 o’clock in the afternoon and I was driving along the road to take my daughter from school. Our plan ...
A.
on his way to the Post Office
B.
stopping off at a shop
D.
under a road built like a bridge
【简答题】My plan was never to humiliate him, but to let him know the truth.