46. The last time I went to the museum was a year ago.
A. I have not been to the museum for a year. B. A year ago, I often went to the museum.
C. My going to the museum lasted a year. D. At last I went to the museum after a year.
47. I haven’t worked in orphanages for years.
A. I haven’t worked in orphanages for long ago.  
B. The last time I worked in orphanages since years ago.
C. I didn’t work in orphanages years ago.        
D. I last worked in orphanages years ago.
48. We don’t let students smoke in the room.
A. We  don’t permit students smoke in the room.
B. We allow students to smoke in the room.
C. We don’t permit students to smoke in the room.
D. We don’t permit students smoking in the room.
49. Mr. Pinchley doesn’t allow his teenage children to go out in the evenings.
A. Mr. Pinchley let his his teenage children go out in the evenings.
B. Mr. Pinchley makes his teenage children stay at home in the evenings.
C. Mr. Pinchley permit his teenage children to go out in the evenings.
D. Mr. Pinchley let his teenage children stay at home in the evenings.