21. He has ___good knowledge of science and ____sense of humour..
A. a , / B .a, a C. / , a D. /, /
22. Don’t always want to arrive at your ___ through shortcut because there may be many difficulties on shortcut that maybe seem shorter and then you will spend more time.
A. target B. aim C. destination D. object
23. He went ___ the plane and just a few hours later he arrived ___---far away from his parents.
A. on aboard; abroad B. aboard; aboard
C. aboard; abroad D. on aboard; on abroad