28. The book was written _____ careful observations and detailed studies.
| A．on the ground of | B．on behalf of | C．on average | D．on the basis of |
Unfortunately, the element Madam Curie devoted all her life her death.
| A．to caused | B．causing | C．to be caused | D．to causing |
Out of the crowded bus , who was dressed in a black suit and waved to a woman.
| A．a tall man stepped | B．stepped a tall man |
| C．did a tall man step | D．did a tall man stepped |
With the help of high technology, in the past few years, electronic business __________to bank industry, travel industry.
| A．applied | B．have applied |
| C．had been applied | D．has been applied |
We all know the truth ______ there are air, water and sunlight, there are living things.
| A．in wherever | B．where | C．that where | D．that |
Look at the mess the boys made! You _______ have taught them how to behave themselves.
| A．must | B．may | C．can | D．should |