函数y=2sinx-sin|x|的值域为 [ ]
A、[-1，1]
B、[0，2]
C、[-3，3]
D、[0，3]
答案：C
Nobody but doctors and those _______ by Dr Smith ______ to enter the patient’s room.
A．invited; is allowed
B．invited; are allowed
C．being invited; is allowed
D．being invited; are allowed
下列反应中属于氧化还原反应的是（ ）
A．CO2+H2O==H2CO3
B．H2CO3==CO2↑+H2O
C．CaCO3+2HCl==CaCl2+H2O+CO2↑
D．CO2+C高温2CO
