.______ 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 |
Mr Smith was so angry at all ________ Robert was doing _________ he walked out angrily.
| A．that; what | B．that; that | C．which; which | D．what; that |
By making friends with the native speakers, one can _________ a lot of their language.
| A．take up | B．set up | C．pick up | D．put up |
The lecture that Mr Chen made this morning gave a strong ___________ on the students.
| A．expression | B．expectation | C．impression | D．reputation |
After the long journey, the Whites returned home, ___________.
| A．safely but tired | B．safe but tired |
| C．safe and tiring | D．safely and tiring |
Only when I made it to the train station _______ that I had left my ticket at home.
| A．have I realized | B．did I realize | C．had I realized | D．would I realize |