31. _____ our earth, otherwise it will be no longer fit for us to live on.
| A．Protected | B．To protect | C．Protecting | D．Protect |
To be frank, I really don’t know what SOS ____________. Can you explain it?
| A．stands by | B．stands for | C．stands up | D．stands with |
Many of the artists who _______ didn’t come.
| A．ought to appear | B．should appear |
| C．had to appear | D．ought to have appeared |
He had led everyone to ______ that his family was very rich.
| A．believing | B．believe | C．be believed | D．be believing |
The company was named Gates Hall ______ a man named James Gates.
| A．in need of | B．in search of | C．with the help of | D．in memory of |
He wanted the girl he was looking forward _____ ____ stay with him.
| A．for; to | B．to; with | C．to; to | D．with; to |