More bison were killed．The bison population is thought ______ from 60 million to just a few hundred between 1850 and 1910.
#96722
A
to have fallen
B
having fallen
C
to fall
D
falling
推荐题目
The lady was so absorbed in her job that she didn't hear a customer ________ at the door.
#88799
A
to knock
B
knocking
C
be knocked
D
knocked
It is reported that the water in the river is becoming worse and worse, the river around the city ____ with waste from factories．
#96043
A
polluting
B
polluted
C
having polluted
D
to pollute
You'd better get all the work _________ before you leave.
#98400
A
finishing
B
to finish
C
finished
D
be finished
It is clear that your ____ English will greatly improve if you can practice ____ wherever you can.
#95991
A
speaking; speaking
B
speaking; spoken
C
spoken; speaking
D
spoken; spoken
We usually take turns ______cleaning ,and today it is my turn ____it
#97241
A
to do; doing
B
doing; doing
C
doing ;to do
D
to do ;to do