改为一般疑问句、改为否定句、对括号部分提问
The sun is heavier than the Earth.(改为一般疑问句)
Dr Zhang works in the space station.(改为一般疑问句)
Dr Zhang has a rest [in the eveing].(对括号部分提问)
There is gravity inthe space station.(改为否定句)
There is a sunrise or sunset [every 45 minutes].(对括号部分提问)