_____the beginning of the 19^th century did scientists know that all matter is made up of atoms.
A,At     B,By     C,Up to     D,Not until

Most people are familiar with the idea that all matter in the universe ________ atoms.

A．makes up         B．makes up of        C．consists in         D．consists of

Most people are familiar with the idea that all matter in the universe ________ atoms.

_____the beginning of the 19^th century did scientists know that all matter is made up of atoms.

A,At     B,By     C,Up to     D,Not until

.______ the beginning of the 19th century did scientists know that all matter is made up of atoms.

A. At          B. By            C. Up to         D. Not until