The scientist and engineer ____ (have) invented a new machine.
A: are
B: was
C: has
D: were
A: are
B: was
C: has
D: were
举一反三
- 青书学堂: They have invented a new ____ washing machine.( )
- If computers ______, many problems on space flight could not have been solved. A: had not been invented B: are not invented C: were not invented D: have not invented
- The factory has produced a new kind of ____. A: machine B: machines C: a machine D: the machine
- Many a young scientist ________ engaged in the research work. A: have B: has C: have been D: has been
- There was an ( __ ) (engineer) problem of the machine.