28. Be careful! The slightest spark（火花）could ______ the fireworks.
| A．set about | B．set off | C．set out | D．set up |
Experts have found that the disease will lead to a greater increase in the number of sufferers unless ________ seriously when the symptom first appears.
| A．treated | B．to be treated |
| C．being treated | D．be treated |
To improve their oral English, everyone in the class is supposed to ________ actively in these discussions.
| A．participate | B．attend | C．enter | D．take |
— Jack, Jane seems unhappy?
— Don’t worry, a funny story will ________ her.
| A．amuse | B．meet | C．tease | D．fool |
The moment their idol took the floor, the excited fans ________ thunderous applause.
| A．ran into | B．burst into |
| C．came into | D．turned into |
________, you'll never be able to persuade him.
| A．However hard may you try | B．Try however hard you may |
| C．Hard as you may try | D．Try hard as you may |