某矿石由前20号元素中的4种组成,其化学式为W m Y n Z p X q 。X、Y、Z、W分布在三个周期,原子序数依次增大,W、Y为金属元素,X原子的最外层电子数是次外层电子数的3倍,W单质能与冷水剧烈反应,Y、Z原子的最外层电子数之和与X、W原子的最外层电子数之和相等,Y、Z位于同周期,Z单质是一种良好的半导体。下列说法正确的是( )
【单选题】In response to foreign organisms, humans produce a variety of antibodies that can bind to the organism. In the production of human antibodies, which one of the following can cause the production of di...
A.
Pretranscription processing of hnRNA
B.
Removal of introns from hnRNA
C.
Addition of a cap to the 5 ′ -end of hnRNA
D.
Addition of a cap to the 3 ′ -end of hnRNA
E.
Alternative sites for synthesizing the poly(A) tail