Dr. Wang teaches biology at a university in the United States, and he has been in America<br />for 20 years.<br />He studies one kind of North American butterfly, just like a migrating bird.<br />This butterfly travels about 4,000 kilometers south in fall.<br />He doesn't understand how the butterflies know when to fly south.<br />If they are even a few days late, they will freeze.<br />And how do all the great-great-grandchildren find the same forest in Mexico every year?<br />This is both puzzling and interesting for many scientists.<br />Many mysteries still need to be discovered by people who are interested in science.<br />Dr. Wang teaches biology at a university in the United States, and he has been in America for 20 years.<br />He studies one kind of North American butterfly.<br />Just like a migrating bird, this butterfly travels about 4,000 kilometers south in fall.<br />He doesn't understand how the butterflies know when to fly south.<br />If they are even a few days late, they will freeze.<br />And how do all the great-great-grandchildren find the same forest in Mexico every year?<br />This is both puzzling and interesting for many scientists.<br />Many mysteries still need to be discovered by people who are interested in science.<br />Where does Dr. Wang teach?<br />Where does Dr. Wang teach?<br />How many years has Dr. Wang been in America?<br />How many years has Dr. Wang been in America?<br />Or, when does the North American butterfly begin to travel?<br />When does the North American butterfly begin to travel?<br />How far does the butterfly travel?<br />How far does the butterfly travel?
（1）
Where does Dr. Wang teach?
A . In a middle school.B . In a primary school.C . At a university.
（2）
How many years has Dr. Wang been in America?
A . 12.B . 20.C . 22.
（3）
When does the North American butterfly begin to travel?
A . In fall.B . In winter.C . In spring.
（4）
How far does the butterfly travel?
A . 40. 000 kilometers.B . About 4. 000 kilometers.C . 400 kilometers.
