请根据括号内汉\英语提示或已给的首字母写出单词的正确形式。
小题1:To our surprise , he made no ____________（解释）of his absence.
小题2:Tibet is a ____________（多山的） province .
小题3:U______________, my computer system broke down again .
小题4:The learner of a second language has many difficulties to ___________(克服)
小题5:His experiment ended in _______(失败).
小题6:He returned from Paris and found his office was under someone else’s________(占领)．
小题7:At that time, hunger was a ______ problem in many countries.（令人不安的）。
小题8:He has made a________(总结)of the main points in the professor’s speech.
小题9:He made some ________(评论)about my dress，and then carried on reading his book.
小题10:Though he is young, he is s_________ to support a large family. (努力)