2. contribute vi. 起促成作用
例句：Various factors contributed to his downfall.
多种因素导致了他的垮台。
3. obstacle n. 障碍(物), 妨碍
例句：She felt that her family was an obstacle to her work.
她感到她的家庭妨碍她的工作。
4. lack n. 欠缺;不足;没有
例句：He can not buy it because of his lack of money.
他因缺钱买不起这个。
5. personnel n. 人员; 员工；全体人�
