The girl arranged to have piano lessons at the training centre with her sister ____ she would stay for an hour.

We often take ________ and do morning ________ every day.

People have always been curious ________ how living things on the earth exactly began.[ ]

There are about more than five ___________"left-behind" students (留守学生) inChina.

下列各项中,没有语病的一项是（ ）