By the year 1889, there were just 541 bison ________ in the whole of North America.
| A．leaving alive | B．to leave alive |
| C．to be left alive | D．left alive |
．Into the dark apartment____ , who was quite surprised when everyone shouted “Happy Birthday”.
| A．did David walk | B．David walked | C．David did walk | D．walked David |
A successful life is a life_____ challenges are met and difficulties overcome.
| A．which | B．where | C．that | D．what |
．Sorry I’m so late, but you cannot imagine__________great trouble I took to find your house.
| A．what | B．how | C．why | D．when |
．The silence of the library is sometimes broken by a sudden cough or the sound of pages_______.
| A．turning | B．turned | C．being turned | D．having turned |
Nearly half a million people are believed_________their homes as a result of the disaster.
| A．to leave | B．to be left | C．to be leaving | D．to have left |