. You can hardly recognize him in the photo, ________?
| A．can you | B．can’t you | C．do you | D．don’t you |
He knows so much about Russia that he's universally acknowledged as a(n) _____ on Russian affairs.
| A．authority | B．routine | C．privilege | D．boundary |
The first few years in the 21st century ______ the rapid rise of China as a world economic power.
| A．witness | B．has witnessed | C．will witness | D．have witnessed |
Visitors to the National Museum can avoid long lines at the ticket booths by purchasing tickets ____.
| A．in advance | B．in detail | C．out of order | D．with caution |
She told me that she would not go with us if it ____ the next day.
| A．was raining | B．rains | C．rained | D．had rained |
I know one of the things I was unsure about was _____ hard it would be to climb this mountain.
| A．what | B．that | C．however | D．how |