1 Optimal atomic clocks can calculate time with /precise/ predetermined/pinpoint/ accuracy. 2 Obelisks and sundials function according to the same basic /structures/principles/crossings. 3 We live in a(n) /season/era/moment/ of rapid technological change. 4 People's /milestone/quest/leap/ for knowledge has led to brilliant inventions. 5 Will you please fit a meeting with the team /on/into/at/ your busy schedule? The museum /features/highlights/depicts/ a wide variety of clocks and watches from around the world. 7 It's time to start your presentation; you've already /spent/ passed/wasted/ enough time. 8 Sundials allowed people to form a rough /amendment/ alternative/estimate/ of time.
I think it is exciting to do tricks, but it might be difficult.
It is really great and very important to help children and it may be fun.
I think it is boring to water flowers, but it is useful.
I think raking leaves may be fan when you do it with your friends and it is useful.
I think it is not useful to wash off graffiti and it may be really boring.
I think it may be interesting to collect secondhand books, but it may be boring for young people.
It is great to do shopping, but it is really boring for boys and for adults.