用a表示DNA，b表示基因，c表示脱氧核苷酸，d表示碱基，则四者的关系是 [ ]
A．
B．
C．
D．
答案：C
能降血压的是( )
A．五加皮、桑寄生B．千年健、臭梧桐C．臭梧桐、稀莶草D．豨莶草、千年健E．蕲蛇、乌梢蛇
London is a most beautiful city in Britain, ____ the River Thames.[ ]
A. located in
B. lied on
C. situated on
D. stood in
