Though ______, many laws of nature exist.
| A．not having been discovered | B．having not been discovered |
| C．not having discovered | D．having not discovered |
He was ______ to find that it was almost impossible to undertake the task.
| A．cast off | B．cast out | C．cast away | D．cast down |
I took a risk to carry out the project, but it ____ in the end.
| A．paid up | B．paid out | C．paid off | D．paid back |
The boys marked ____ a football court on the playground.
| A．out | B．up | C．down | D．with |
Thoughts can also be expressed _____ music.
| A．though means of | B．by way of |
| C．with the method of | D．by means of |
Many died or returned home, but most remained in California to _______ for themselves in the new town.
| A．making a life | B．make a live |
| C．make alive | D．make a life |