His _____ behavior made everyone nervous. He was always rushing to open doors and perform other small tasks, apologizing unnecessarily for any inconvenience that he might have caused.

A. magnates 　B. magnets 　C. machine 　D. magnitudes

A. neck-less 　B. neck-lace 　C. reckless 　D. rack-less

A. variably 　B. invariably 　C. invaluably 　D. invalidly

A. mind 　B. idea 　C. intention 　D. wish

A. stack 　B. stage 　C. stagnate 　D. stamp

A. to 　B. so 　C. go 　D. do

A. occurring 　B. to occur 　C. occurs 　D. occur

A. find 　B. found 　C. founded 　D. founding

A. a leading astronomer,

B. who, as a leading astronomer,

C. was a leading astronomer,

D. a leading astronomer who

A. the stress it is greater

B. greater is the stress

C. greater stress is

D. the greater the stress