Don't use water to put out the fire if oil catches fire. As is known, oil ______ float on water.
| A．shall | B．must |
| C．may | D．will |
There came a stranger with his cap pulled over his face, ______ I thought seemed curious about what I was carrying．
| A．that | B．who | C．whom | D．which |
All people in the company voted for Mr．Smith．His management and strong character as well as his kind-heartedness made _____ he was as CEO．
| A．who | B．which | C．what | D．whom |
--- Hey, Tom．I think I am quite familiar with these photographs．
--- It is impossible for anyone_________ them before, because Mr．Newman had them developed today．
| A．having seen | B．to have seen | C．to see | D．seeing |
---Is there anything wrong, Bob? You look sad．
---Oh, nothing much．In fact, I ____ of my friends back home．
| A．have just thought | B．was just thinking |
| C．would just think | D．will just be thinking |
The genetic engineering, ______ progress has been very rapid recently, is perhaps the most important of all the sciences．
| A．to which | B．with which | C．in which | D．for |