问题补充：
单选题Psychologicalstudiesshowthatsomepeoplearequick-tempered_____.A.at heartB.on purposeC.in personD.by nature
答案：
D解析by nature 天生，生来。in person 1）亲自，亲身：I shall be present at the meeting in person.(我将亲自出席会议。)2）身体上，外貌上：In person he was handsome, strong and healthy.(他面目清秀，体格强壮。)at heart 1)内心里，实质上：His manners are cold, but he is at heart a kind man. (他的言谈举止有些冷淡，但实际上他是一个好心肠的人。)2）考虑的是......：When I say don eat sweets, I have your health at heart.(我叫你别吃果糖，是考虑到你的健康。)on purpose 故意地。
