Issac Newton, a British scientist, who lived over 300 years ago, said that he saw ______ than others because he stood on the shoulders of giants.

A．advantages
B．disadvantages
C．point
D．cases

A．To keep out boats that are too large for the canal.
B．To measure the tonnage of canal boats.
C．To load and unload the cargo.
D．To change the depth of the watch