已知数列{an}的通项公式an=n2-3n-4(n∈N*),则a4等于( )
A.1
B.2
C.0
D.3
∵an=n2-3n-4(n∈N*),
∴a4=42-3×4-4=0,
故选C
—Where is Sam?
—He ________ in the river.
A. swims
B. are swimming
C. is swimming
D. is swiming
要求崩解时间为30分钟的是()
A.舌下片
B.含片
C.口服片
D.肠衣片
E.糖衣片