28. A heavy snow promises a good harvest, _____ is often the case.
20. The flu is believed________by viruses.
19. They________a lot of suggestions for improving the workers’ living conditions.
18. After having gone____-far, I didn’t want to turn back.
17. One of the mottos for the park makes_____clear that science and business can and must work together to build the future.
16. This experiment turned out to be____failure, but, as we know, success often comes after___failure.