Plants use the carbon, along with sunlight, for growth, and （） oxygen into the atmosphere in a process known as photosynthesis.

If things are going badly, the optimist acts quickly, l...

单项选择题If things are going badly, the optimist acts quickly, looking for （） and forming a new plan of action.

Some people wait for （） to come knocking. Some people s...

单项选择题Some people wait for （） to come knocking. Some people sought it out.

He felt a bit （） because her life seemed completely out...

单项选择题He felt a bit （） because her life seemed completely out of balance.