The custom has been___since the 18th century
_______the thick clouds, you would find the kite in the sky easily.
Experts say ________ to sunlight for too much time will do harm to one’s skin.
—What about the student in your class, Mr. Wang? —The doctor said that sleep caused him poor memory and poor concentration.
Before driving into the city, you are required to get your car ____.
To avoid on how to use the word, you’d better refer to a dictionary.