TOEFL

____ a ball-and-socket joint, the elbow is a simple hinge joint. A. while the shoulder B. while the shoulder is C. the shoulder is D. the shoulder

Pressure differences make the eardrum vibrate _____ the ear. A. enters the sound waves B. as sound waves C. sound waves enter D. as sound waves enter

Bears cannot see well _____ small eyes. A. bears have B. because having C. because they have D. because of bears

_____ at the Isthmus of Panama, so animals were able to migrate between North and South America. A. A land bridge existed B. when a land bridge existed C. a land bridge D. with a land bridge

A car has several sections with moving parts, ____ of those parts is essential. A. good lubrication B. well lubricated C. and good lubrication D. and well lubricated

An optical microscope magnifies as much as 2.000 times, but an electron microscope ____ as much as a million times. A. magnifying B. it magnifies C. can magnify D. magnify it

____ mostly made of granite, it also contains some human-made materials. A. The Empire State Building B. The Empire State Building is C. Although the Empire State Building D. Although the Empire State Building is built

A spacecraft is freed from friction _______ launched into space. A. it B. it is C. after is D. after it is

If scientific estimates are accurate, ____ with the Earth about 20,000 years ago. A. the Canon Diablo meteorite collided B. the collision of the Canon Diable meteorite C. the Canon Diablo meteorite colliding D. colliding the Canon Diablo

_______ with their surrounding, or they hide in crevice for protection. A. Lobsters B. Lobsters blend C. Lobsters blending D. Because lobsters blend