The artist was asked to show some paintings at the contest because ________.
A、he painted very good
B、they believed he painted well
C、of their belief that he was an good artist
D、the judges had been told of his talents

由于碘单质的氧化性不强，直接碘量法只能测定一些还原性很强的物质。 A、正确 B、错误

单项选择题由于碘单质的氧化性不强，直接碘量法只能测定一些还原性很强的物质。
A、正确
B、错误

左下势独立动作,当右腿屈蹲变仆步时,伸出的左腿脚跟先落地( ) Inthe action of Left Sn...

判断题左下势独立动作,当右腿屈蹲变仆步时,伸出的左腿脚跟先落地( ) Inthe action of Left Snake Creeps Down, your left heel touch the groundwhen right leg do Crouch Stance.
A、正确
B、错误

（）提高催化剂的使用效率。A．增加活性 B．减少中毒 C．回收使用 D．反复利用

多项选择题（）提高催化剂的使用效率。