Manipulators that mimic human motions ________available for a long time.
A: have
B: been
C: have been
D: is
A: have
B: been
C: have been
D: is
举一反三
- These magazines___ in the library for a long time. A: have kept B: are keeping C: have been keeping D: have been kept
- How _ have you been to Beijing? A: much time B: long C: long a time D: manytimes
- These magazines ______ in the library for a long time. A: have kept B: had kept C: have been kept D: were kept
- The program is ________to help people who have been out of work for a long time.
- How ______ have you been to Beijing? A: many times B: much time C: long a time