题目

肉毒杆菌是一种致命病菌，在繁殖过程中会分泌毒素。军事上常将这种毒素用于生化武器。人们食入和吸收这种毒素后，神经系统将遭到破坏。该毒素是由两个亚单位（每个亚单位为一条肽链盘曲折叠而成）组成的一种生物大分子。下面是肉毒类毒素的局部结构式，据此判断下列说法中正确的是（） A . 组成肉毒素的元素一定只有C，H，O，N B . 图中该片段由5种氨基酸组成，有4个肽键 C . 该片段所在的肽链至少含有1个氨基和1个羧基 D . 高温下可使肉选词填空present, minute, one, physics, last【1】In the UK, each lesson ________ for an hour.【2】There is a big sports meeting ________ a year in our school,【3】My home is not far, it’s only five ________ by bicycle.【4】Of all the subjects, I like _______ best and I want to be a scientist when I grow up.【5】Every morning our head teacher comes to see if all the students are ________.