填空题 Red and green light, if mixing , in the right proportion, will give us yellow.
A. Red and green
B. if mixing
C. in
D. will give
【正确答案】
【答案解析】B 应改为mixed。[解析] 因为mix和主语“red and green light”是动宾关系,因此要用过去分词。if mixed=if they are mixed。本句的意思是:“红光、绿光混合到一起,如果比例正确的话,就会呈现黄色。”