何为回波时间(TE)?
参考答案:
是指射频激励脉冲与产生回波中心点之间的时间。在自旋回波序列中,TE是90度脉180度脉冲间的2倍。
阅读下面短文,写出括号中所给动词的正确形式,使短文意思完整。
Mr. Johnson had a factory. He once saw on TV that animals could be taught 1 (do) some work for
people if they 2 (give) to eat. He loved the idea. He thought it would be good to have a dog look after
his house and an elephant do some heavy jobs in his factory. He bought a dog and an elephant in the market
and 3 (decide) to teach them to do some work for him. Of course, he also bought a lot of food for them.
Several months later, the dog and the elephant 4 (become) fatter and fatter, but they couldn't do any
work for him. At last, Mr. Johnson had to 5 (give) up.
1.______ 2.______ 3.______ 4.______ 5.______
我国宪法序言中的规定大都具有宣誓性质,不规定具体的权利义务内容。针对这些规定说法正确的是( )。
A.法律都应当规定具体的权利义务内容,因此宪法序言中这些规定不具有法律效力
B.宪法不同于一般法律,有一些宪法规范不规定权利义务的内容,这些宪法规范不具有法律效力
C.宪法不同于一般法律,宪法规范都不规定权利义务的内容,但这些宪法规范具有法律效力
D.宪法序言是宪法的组成部分,虽然大都没有规定权利义务的内容,但这些宪法规范具有法律效力