A.1/5~1/3 B.1/4~1/3 C.1/3~1/2 D.1/2~2/3
A.3s B.5s C.10s D.15s
A.心肌收縮力增強(qiáng) B.心輸出量降低 C.機(jī)體代謝率降低 D.心肌收縮力降低