---I don’t understand why Catherine stopped short _____ she ought to have continued.
---It’s obvious that she lacked self-confidence.
A. when B. while
C. if D. as
Never turn down a job because you think it’s too small. You don’t know _____ it can lead.
A. how B. where
C. whether D. what
A scientist’s attempt to produce the world’s first gene-edited babies _____ are immune to HIV has sparked controversy in academia and the public.
A. as B. who
C. whom D. whose
____ clear goals, we become strangely loyal to performing daily doings until we become slaves of them.
A. On top of B. In the silence of
C. On account of D. In the absence of
Computer-controlled robots are taking over jobs in many industries, which used to be done _______.
A. artificially B. manually
C. comprehensively D. gradually
Her doctor indicated that even adding a(n) _____ amount of daily exercise would dramatically improve her health.
A. modest B. equal
C. considerable D. exact
