The scientist __________ the experiment for half a year, but he _______ yet.
| A．made; didn’t succeed | B．made; hasn’t succeeded |
| C．was making; didn’t succeed | D．has been making; hasn’t succeeded |
Although she brushed the old pot_______, she could not make it completely clean, which made her very upset.
| A．roughly | B．thoroughly |
| C．instantly | D．occasionally |
Mr. Smith is always on time for everything. How ____ it be that he was late for the important meeting?
| A．should | B．can |
| C．may | D．must |
---Your grandfather still seems very energetic, although he is already in his seventies now.
---Yes, he _______in the army for three years when he was young.
| A．would serve | B．served |
| C．had served | D．has served |
Many plants could move northward and toward the Pacific coast _______rising temperatures and changes in rainfall.
| A．for fear of | B．in defense of |
| C．by means of | D．in reaction to |
Once a schedule is made, by strictly _______ it, you can avoid putting off till tomorrow what should be done.
| A．arranging | B．measuring |
| C．observing | D．presenting |