题目

Not until _______ 18 years old _______ a right to vote.    A. have you reached; can you have    B. have you reached; you can have    C. you have reached; can you have    D. you have reached; you can have 答案：CX、Y、Z三种固体物质的溶解度曲线如右图所示．下列说法中不正确的是A.分别将X、Y、Z的饱和溶液的温度从t2℃降低到t1℃，只有Z无晶体析出B.t℃时，用100克水配制相同质量、相同质量分数的X、Y、Z的溶液，所需溶质质量最多不超过SyC.当X中含有少量Y时，可用结晶法提纯XD.t2℃时，三种物质的饱和溶液中溶质的质量分数X＞Y＞Z