下列运算中,正确的是[ ]
A.a4a5=a20
B.a12÷a3=a4
C.a2+a3=a5
D.5a-a=4a
答案:D
肺痈溃脓期的主要病理是()
A、热伤肺气
B、热壅血瘀
C、肉腐血败
D、热毒留恋
E、痰浊上蒙
You need to take notes at the meeting so make sure _________ a pen and some paper with you.
A.bring
B. to bring
C.bringing
D.not bring