A:DNA和RNA在核苷酸上的不同点只在②方面
B:人体内的②只有一种
C:③在生物体中共有8种
D:人体内的③有5种
____ (judge) from his ____ (excite) news, his friends have found the key to ____ (solve) the problem.
如图,该图中不同的线段数共有 ____条.
已知下列信息:a.
b.