某元件的电压U和电流I的实际方向相反，电流从“+”端流出，发出功率，则此元件起电源作用。

34P.将一维数组a的第i个元素的地址赋给指针变量p的语句是p=&a[i];

34p.将一维数组a的第i个元素的地址赋给指针变量p的语句是p=&a[i];

4．从一个标准差为15的总体中抽出一个样本量为49的样本，样本均值为25，在95%的置信水平下，边际误差等于（）。

设边际替代率MRSXY＝Y/X，I＝80，PX=2,PY=1，最优消费组合为()

Directions:Choosetheonethatbestcompletesthefollowingsentences.49.—“Don’ttellhimthenews.”shesaid.—Shetoldme_______________himthenews.

49.Aflu_________issweepingthroughNewYork.

49.Whathedidwasvery______,forhemighthavehurtsomebody.-

49.Intheauthor’seyes,motorheadsare_______.

49.Whatdoestheauthorthinkofteachingability?

25.I'llneverforgettheday____Iboughtmyownguitarwithmyownmoney.

49.原文:JimleftAustraliabeforecompletingtheprojectandinafitofangervowednevertoreturn.问题句:JimneverreturnedtoAustraliatoseethecompletedbuilding.

26.I’llneverforgettheday____Iboughtmyownguitarwithmyownmoney.

49.原文:AlthoughHendersonneverlikedtheprospectofabusinesscareer,hestayedwithittopleasehisfamily.问题句:Hendersonpursuedabusinesscareerbecauseitwaswhathisfamilywanted.

3.I’vebeenwrestlingwiththequestionof...这个句式是表达肯定的意思。