The doctor was reading an article ______ the class.
| A．for | B．by | C．towards | D．to |
________ scores of times, but he still couldn't understand it.
| A．Having explained |
| B．Having been explained |
| C．Though it was explained |
| D．It was explained |
________ I couldn't fully understand what he wanted to show in his paintings, I thought his works were quite impressive.
| A．As | B．Since | C．If | D．While |
Jim came back early last night. It was not yet eight o'clock ________ he got home.
| A．before | B．that | C．when | D．until |
If we work with a strong will, we can overcome any difficulty, ________ great it is.
| A．what | B．how | C．however | D．whatever |
Life is filled with things we have no control over, ________ ourselves, we can control.
| A．for | B．and | C．so | D．but |