下图为研究草蜢呼吸速率而设计的实验装置及结果,其中毛细管截面积为Rmm2,则草蜢的呼吸率(以吸入氧气的体积为准)应为()
A. R×(L+L)mmh
B. 2R×Lmmh
C. 2R×(L+L)mmh
D. 2R×(L—L)mmh
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AllofthefollowingareengagedinfishingEXCEPT().
Avesseltrawling
B. Avesseltrolling
C. Avesselsettingnets
D. Avesseltendinglines
被子植物无孢子生殖的胚来自()
A. 未受精的卵细胞
B. 助细胞、反足细胞或中央细胞
C. 珠被或珠心细胞
D. 大孢子母细胞
Aninclinedsemisubmersiblewithaveryshortrollingperiodaboutaconstantangleoflistislikelytohave().
A. anoff-centerTCG
B. anLCGgreaterthanlevelvesselLCB
C. anegativeGM
D. excessivefreesurfaces
Openthe()beforestartinganaircompressor.
A. unloadvalve
B. coolingwater
C. oilcup
D. sump