_____ three influenza type A virus subtypes（子类型） have been found in pigs．
| A．By far | B．As far as | C．So far | D．Till far |
Some people like drinking coffee,for it has___effects
| A．promoting |
| B．stimulating |
| C．enhancing |
| D．encouraging |
The law___the sale of cigarettes to people under the age of 16
| A．encourages |
| B．allows |
| C．forbids |
| D．helps |
I forbid___here.Who has permitted you___here?
| A．smoke;smoking |
| B．smoking;to smoke |
| C．smoking;smoking |
| D．to smoke;smoking |
I haven’t read___of his books,but judging from the one I have read,I think he’ll make a very promising writer
| A．any |
| B．none |
| C．both |
| D．either |
The great trouble he___show us how to run the machine___him completely tired out
| A．took to;made |
| B．takes to;make |
| C．took;make |
| D．takes to;to make |