重交通道路石油沥青中规定蜡含量不大于（）。
A.3.0％
B.4.0％
C.4.5％
D.5.0％
参考答案：A
During the opening ceremony, “Miss Smile” has won the hearts of Chinese Internet users after being caught _____ the same smile for nearly 20 minutes．
A．fixed
B．to be fixed
C．to fix
D．fixing
下列分子或离子，含有配位共价键的是（）。
A.NH4+
B.N2
C.CCl4
D.CO2
