_____the climate changes so much has caused many discussions among the scientists.
| A．What | B．Which | C．When | D．That |
He broke his legs while ＿＿＿＿＿.
| A．riding | B．ride | C．was riding | D．rode |
If you go to Xi’an, you will find the palaces there more magnificent than commonly＿＿.
| A．supposing | B．supposed | C．to suppose | D．suppose |
—— He hasn’t gone to the office up to now.
—— Well, he ＿＿＿＿＿.
| A．should | B．ought to | C．ought to go | D．ought to have |
—— Have you watered the flowers?
—— No, but ＿＿＿＿＿.
| A．I am | B．I’m going | C．I’m just going to | D．I will go |
Mr. Black, ＿＿＿＿＿ born in Kentucky, lived and practiced law in Missouri.
| A．was | B．he was | C．although | D．who he was |