The first day of ______ year is called ______New Year’s Day. 

A. the; /     B a; /      C. the; a       D. the; the

只发生缩短而张力保持不变的肌肉收缩叫做（）.

A.等张收缩

B.等长收缩

C.单收缩

D.强直收缩