以下描述正确的是（） A.药物的LD50值越小，则其毒性越大 B.药_爱下问搜题

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问题多项选择题

以下描述正确的是（）

A.药物的LD50值越小，则其毒性越大

B.药物的LD50值越小，则其毒性越小

C.治疗指数（TI），在试验动物作安全性评价的一种常用指标，是LD/ED

D.半数有效量（ED50）：指引起50%阳性反应或50%最大效应的剂量

E.在临床上，有时用药物最小有效量和最小中毒量之间的距离表示药物的安全性，称安全范围，其距离愈大愈危险

答案

参考答案：A, C, D

选择题

A group of young Americans have come to Beijing for a visit. Half of them, ___is, 50 persons, can speak Chinese fluently.

A．that

B．which

C．who

D．it

完形填空

Last weekend, my kids along with a few other kids from the neighborhood volunteered to help me wash my car．My 10-year-old daughter came up with the idea of 31 other people’s cars as well．It was pretty   32  outside and I had no plans to   33  being in the bright sun．She   34  wanted to give lemonade（柠檬汽水）to passers-by for free．I had seen little kids 35  and sell fresh lemonade for a small cost but not free．Although I felt   36 , I decided to help her．
37  she asked me, “What if we   38  this a smile car wash?” I couldn’t hold back my tears and   39  her and the other kids to go outside the house and come up with   40  ideas．While I kept myself busy in drying the car, the gang walked up to me with a（n） 41  with beautiful images of smiles．They had “Free Car Wash” written on it and the   42  of their exercise was “smile”．It was pretty neat to see a team of kids ranging 5-11 years with the   43    to do something for others．
All that seemed   44   and came right from their heart．Nothing seemed to   45  to them: their playtime, the heat outside—they just wanted to   46 others and do something nice in the community!
I helped them make some fresh lemonade and brought out some additional   47 to help clean cars．Passers-by were   48   and one even shouted back to them saying “God Bless You, my kids…” One of them even tried giving them 5 dollars, which they refused．A pretty heartwarming   49  !
I feel blessed by being   50  by such wonderful and loving souls．

C．imagination

B．disappointing