The author compares cells with water balloons in order to ______.

A． make you think of summer

B． help you visualize the cells

C． show how rubber is elastic

D． show how many shapes cells can have

[单选题]The writer compares turtles to mountain climbersA． because they lay their eggs in mountain areas ______.B． to give you a picture of how hard they workC． to tell you that they like to climbD． to tell you that mountain climbers are as slow as turtles

[名词解释] stem cells, SC (干细胞)

[单选题]二巯丙醇(BAL)A．是最常见的氨羧螯合剂，可与多种金属形成稳定可溶的金属螯合物排出体外B．化学结构、作用与依地酸相似，但促排铅的效果比依地酸好C．为含有活性巯基（-SH）化合物，药物进入体内后可与某些金属形成无毒的、难解离的螯合物由尿排出D．作用与二巯丙醇相似，但疗效高，不良反应较少E．主要用于治疗锑、铅、汞、砷、铜等中毒。近来发现用该药口服治疗铅中毒有效

[单选题,A2型题,A1/A2型题] 二巯丙醇（BAL）（）A . 是最常见的氨羧螯合剂，可与多种金属形成稳定可溶的金属螯合物排出体外B . 化学结构、作用与依地酸相似，但促排铅的效果比依地酸好C . 为含有活性巯基（-SH）化合物，药物进入体内后可与某些金属形成无毒的、难解离的螯合物由尿排出D . 作用与二巯丙醇相似，但疗效高，不良反应较少E . 主要用于治疗锑、铅、汞、砷、铜等中毒。近来发现用该药口服治疗铅中毒有效

[单选题]二巯丙醇(BAL)A.是最常见的氨羧螯合剂，可与多种金属形成稳定可溶的金属螯合物排出体外B.化学结构、作用与依地酸相似，但促排铅的效果比依地酸好C.为

[单选题]二巯丙醇(BAL)A.是最常见的氨羧螯合剂，可与多种金属形成稳定可溶的金属螯合物排出体外B.化学结构、作用与依地酸相似，但促排铅的效果比依地酸好C.为

[单选题]集油槽COLLECTOR CELLS位于哪个油箱？（）A . 外格油箱B . 中央油箱C . 内格油箱D . 配平油箱内

[名词解释] 狼疮细胞(1upus erytheumatosus cells LEC)

[单选题]胃底腺的Chief Cells可分泌（）。A . 盐酸B . 胃蛋白酶C . 胃蛋白酶原D . 内因子

[单选题]The author intends to .A．stress the advantages of TV t o people’s livesB．persuade women to become more independntC．encourage people to improve their reading skillsD．introduce the readers some websites such as Google