【单选题】According to the Para. 2, when it comes to gap years,______.
A.
the popularity of gap years results from an increasing number of charities
B.
Prince William was working hard during his gap year
C.
gap years arc not as fashionable as they were ten years ago
D.
a well-structured gap year is a guarantee of university success
【单选题】According to the Para. 2,when it comes to gap years, ______.
A.
the popularity of gap years results from an increasing number of charities
B.
Prince William was working hard during his gap year
C.
gap years are not as fashionable as they were ten years ago
D.
a well-structured gap year is a guarantee of university success
【简答题】减数分裂过程中,前期I的()是同源染色体两两配对,出现联会现象的时期。
【单选题】There an enormous gap between the income of the rich and poor. Gap means _____
B.
the American clothes brand GAP
【多选题】关于GAP 说法,正确的有
A.
从事中药材生产的企业必须通过GAP 认证并取得GAP 证书
B.
GAP 适用于中药材(包过植物药和动物药)生产全过程
【单选题】下图示意某生物细胞的减数分裂时,两对同源染色体联会时出现异常的“十字型结构”现象,图中字母表示染色体上的基因。据此所作推断中,错误的是 [ ]
C.
该生物基因型为HhAaBb,可能属于二倍体生物
【单选题】倒位(inversion)是指一条染色体上同时出现两处断裂,中间的片段扭转l80°重新连接起来而使这一片段上基因的排列顺序颠倒的现象。在同源染色体联会时会有不同情形,其中:()
A.
倒位区段很小时,同源染色体在倒位区段可能优先配对
B.
倒位区段很大(包括染色体的大部分)时,倒位的染色体可能倒过来和正常的染色体配对
C.
倒位区段很小(包括染色体的极短部分)时,正常的染色体可能倒过来和倒位的染色体配对
D.
倒位染色体与正常染色体大小悬殊时,则通过形成倒位环进行同源区段的联会
E.
只要有倒位,就会在减数分裂中同源染色体配对时产生典型的倒位环(环中倒位染色体区段倒过来)
【判断题】( )晶闸管中频电源中,用记忆示波器接在逆变桥输出端可看到衰减振荡波形。
【多选题】MCX 固相萃取柱净化包括以下哪些步骤: