In order to prevent people from crying, the geneticists have invented the no-tears union__ .
Medical researchers are painfully aware that there are many problems __ (他们至今没有答案).
People will experience negativity in the workplaces when they lose ______.
He said he worked hard so as to _______ (不辜负他母亲的希望).
According last paragraph, the old national speed limit related to ______.
When the passenger woke up,______.(他发现自己躺在医院的病房里).