Làm và giải thích chi tiết 21. It takes years to ________ a foreign language. A. access B. master C. outnumber D. address 22. The sky is getting dark. It________ rain is on its way. A. looks B. looks like C. seems to D. will be 23. I am________ several important letters but nothing has arrived. A. expected B. looked forward to C. waiting D. expecting 24. I usually wear skirts but today I ________ trousers. A. wearing B. am wearing C. wear D. wears 25. Preserving natural resources________ of great importance. A. is B. are being C. have been D. are 26. Your voice reminds me of somebody, but I can’t remember________ A. it is B. who is C. who he is D. whom 27. I don’t________ locking the door. Let me double-check A. remember B. forget C. remind D. A & B are correct 28. The flat________ of three bedroms, with a kitchen and a bathroom. A. composes B. contains C. includes D. consists 29. After Mary________ her degree, she intends to work in her father’s company. A. will finish B. is finishing C. finishes D. will have finished 30. The boy, along with his classmates, ________ just paid me a visit. A. has B. have C. are D. is