Chọn một phương án đúng A, B, C hoặc D để điền vào chỗ trống trong đoạn văn sau. (1,0 điểm 
Although most families in the United States enjoy a high living standard, many American women have to work hard at home and in their offices! Despite their husbands share of the housework, it is women (17) ______have to do most of the housekeeping tasks. In single-parent families, the mothers may not have many children to (18), ______ care of, but they have to raise their families alone and have to provide for all the housekeeping money. (19) ______ , the single mothers have to work very hard to earn their living. Moreover, in spite of the fact that the single mothers have all the modern (20)______ at their homes, they find that bringing up their teenage children alone is not easy. 
17. A. which                 B. who                          C. when                    D. whom 
18. A. keep                   B. put                           C. get                         D. take 
19. A. Therefore          B. Although                 C. Moreover             D. Because 
20. A. convenient        B. conveniences         C. conveniently        D. convent