Experts say walking is one of the best ways for a person to _______ healthy.
| A．maintain | B．stay | C．live | D．preserve |
Please excuse me _______ your letter by mistake.
| A．to open | B．to have opened | C．for opening | D．in opening |
After describing the planned improvements, she went on _______ how much they would cost.
| A．to explain | B．explaining | C．to be explaining | D．having explained |
The film star walked to his car, ______ a crowd of journalists.
| A．followed by | B．following by | C．to follow | D．to be followed by |
_______ on time, this medicine will be quite effective.
| A．Taking | B．Being taken | C．Taken | D．Having taken |
When I handed the report to John, he said that George was the person _______.
| A．to send | B．for sending it | C．to send it to | D．for sending it to |