If you don’t know what this means, _____ the dictionary.
| A．look into | B．look up | C．look over | D．refer to |
Mary as well as her sisters ____ Chinese in China.
| A．are studying | B．have studied | C．studies | D．study |
Neither Tom nor Jack and I ____ his students.
| A．are | B．am | C．is | D．was |
The rich ____ not always happy.
| A．are | B．is | C．has | D．have |
I, who____ your friend, will try my best to help you with your English.
| A．am | B．is | C．are | D．be |
The United States of America _____one of the most developed countries in the world.
| A．is | B．are | C．was | D．were |