多肽链的结构是具有______的，因此，在书写时把______末端写在肽链的______边，把______末端写在______边。
方向性；氨基；左；羧基；右
We are taught that a business letter should be written in a formal style ________ in a personal style. [ ]
A. rather than
B. other than
C. better than
D. more than
多由关节积液或关节周围软组织炎症引起，病程长者由滑膜慢性炎症后的肥厚而引起属于（）
A.晨僵
B.关节肿胀
C.关节畸形
D.疼痛与压痛
E.关节功能障碍
