.We cannot figure out ____quite a number of insects, birds, and animals are dying out.

. _____is known to us all is that the old scientist, for____ life was hard in the past,still works very hard in his eighties.

.We live day by day ,but in the great things, the time of days and weeks ______so small that a day is unimportant.

.Having checked the doors were closed, and _____all the lights were off, the boy opened the door to his bedroom.

.A woman tearfully explained _____she had recently lost her husband in a car accident.

..His grandfather was among the first to settle in ____is now a famous holiday center.

.Get involved in sports or other activities you enjoy______you can meet people who like what you like.

.The Gate of Fortune, from ____top visitors can enjoy a wonderful sea view, will attract lots of tourists.

.In the cave they found the very book, the cover of _______was torn.

.By serving others, a person focuses on someone other than himself or herself,_____can be very eye---opening and rewarding.