无症状，但静息、动态时或负荷试验心电图有盯段压低，T波压低变平或倒置等心肌缺血的客观

Most plants can make their own food from sunlight, (1) some have discovered that stealing is an easier way to live. Thousands of plant species get by (2) photosynthesizing, and over 400 of these species seem to live by pilfering sugars from an underground (3) of fungi(真菌). But in (4) a handful of these plants has this modus operandi been traced to a relatively obscure fungus. To find out how (5) are (6) , mycologist Martin Bidartondo of the University of California at Berkeley and his team looked in their roots. What they found were (7) of a common type of fungus, so (8) that it is found in nearly 70 percent of all plants. The presence of this common fungus in these plants not only (9) at how they survive, says Bidartondo, but also suggests that many ordinary plants might prosper from a little looting, too.

Plants have (10) relations to get what they need to survive. Normal, (11) plants can make their own carbohydrates through photosynthesis, but they still need minerals. Most plants have (12) a symbiotic relationship with a (13) network of what are called my corrhizal fungi, which lies beneath the forest (14) . The fungi help green plants absorb minerals through their roots, and (15) , the plants normally (16) the fungi with sugars, or carbon with a number of plants sharing the same fungal web, it was perhaps (17) that a few cheaters—dubbed epiparasites—would evolve to beat the system. (18) , these plants reversed the flow of carbon, (19) it into their roots from the fungi (20) releasing it as "payment.\

5（）

A.others

B.the others

C.other

D.the other

动物生来就有的，由动物体内的_________所决定的行为，称为先天性行为。

散装液化气体是指在37.8℃时绝对蒸气压力超过（）kg/cm²的液体散装货物。

A．0.8

B．1.8

C．2.8

D．3.8

管道的公称直径DN是表示管道的实际内径。

色相对比以任意两色或三色并置在一起，因（）之间的差别形成的对比，称色相对比。

A.色相

B.色度

C.纯色

D.亮度