1) We were prevented ... entering the building. A. for B. off C. by D. from 2) Oil and gas ... for 60% of our exports. A. pay B. account C. call D. place 3) The hotel ... a shoe-cleaning service for guests. A. provides B. gives C. lends D. offers 4) Mrs. Xuan, ... youngest child has just won the first prize in the English Speaking contest, feels very happy now. A. her B. who C. whom D. whose 5) We won't go camping near that river ... it is seriously polluted. A. when B. as C. but D. and