题目

丙烯酸(CH2=CH— COOH)的性质可能有：①加成反应②酯化反应③中和反应④氧化反应 A．只有①②                               B．只有①②③C．只有①②④                            D．①②③④ 答案：D    丙烯酸中，能发生①④，—COOH能发生②和③。By the time he leaves university, he ______ much work experience so long as he takes a part-time job. [　　] A．will have gainedB．has gained C．may have gainedD．will gain