题干

下列有关免疫的叙述正确的是                                    (   )

A:机体接受同种抗原再次刺激时,浆细胞全部由记忆细胞增殖分化而来

B:浆细胞分泌的抗体能特异性识别抗原,但浆细胞不能识别抗原

C:受抗原刺激后的淋巴细胞,其核糖体、内质网和高尔基体的活动增强,从而导致细
胞周期变长

D:T细胞分化形成的效应T细胞和记忆细胞,只有前者细胞膜上具有相应抗原的受体

上一题 下一题 0.0难度 选择题 更新时间:2011-11-12 09:42:39

答案(点此获取答案解析)

B

同类题3

根据短文理解,选择正确答案。

    “Croeso I Gymru!,” If you don't know what this means, read on to find out more.

    When you cross over the border from England into Wales, you don't have to show your passport but you do notice a difference immediately. All the road markings and signs are shown in two languages — English and Welsh (威尔士语). Not all visitors to Britain know that other languages are spoken here. There's the Gaelic (盖尔语) language in Scotland and a few people speak Cornish (康沃尔语)in the southwest of England, but the most widely spoken language in the UK besides English is Welsh.

    Perhaps the first Welsh word you'll see on the road into Wales is ARAF. There's a helpful English translation next to it — SLOW. As you can see, Welsh looks quite different from English. It sounds very different, too. Welsh looks and sounds so different from English because it's a Celtic language. Celtic cultures still exist around the edges of the UK — in Wales, Scotland and Northern Ireland and also in parts of France. For hundreds of years, almost everyone in Wales spoke Welsh, but nowadays there are about 600 thousand Welsh speakers — around 20% of the population.

    So is Welsh dying out? Not at all! Nowadays, all school children in Wales study Welsh and many choose to go to an all Welsh-speaking school. You can get public information in Welsh, speak Welsh in court or take a course at university in Welsh. People surf the Internet in Welsh, keep up with friends on Facebook and write blogs in Welsh.

    By the way, “Croeso I Gymru!" means “Welcome to Wales!” 一 I hope you'll be able to visit it one day.