Even more than mountainside slides of mud or snow, naturally occurring forest fires promote the survival of aspen trees. Aspens' need for fire may seem illogical since aspens are particularly vulnerable to fires; whereas the bark of most trees consists of dead cells, the aspen's bark is a living, functioning tissue that-along with the rest of the tree-succumbs quickly to fire.
The explanation is that each aspen, while appearing to exist separately as a single tree, is in fact only the stem or shoot of a far larger organism. A group of thousands of aspens can actually constitute a single organism, called a clone, that shares an interconnected root system and a unique set of genes. Thus, when one aspen-a single stem -dies, the entire clone is affected. While alive, a stem sends hormones into the root system to suppress formation of further stems. But when the stem dies, its hormone signal also ceases. If a clone loses many stems simultaneously, the resulting hormonal imbalance triggers a huge increase in new, rapidly growing shoots that can outnumber the ones destroyed. An aspen grove needs to experience fire or some other disturbance regularly, or it will fail to regenerate and spread. Instead, coniferous trees will invade the aspen grove's borders and increasingly block out sunlight needed by the aspens.
According to the passage, which of the following would occur if an aspen grove failed to regenerate periodically?
Individual aspens would cease to produce hormones.
Individual aspens would grow outward instead of upward.
The root system of the grove's clone would die.
The grove would lose its access to sunlight.
Soil conditions in the grove would become unfavorable for the growth of aspens.
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正确答案是 D。文章指出,如果不及时重新生长,这片杨树林会遭到其它针叶树的侵略,这些针叶树会堵死杨树所需的阳光。因此,选项 D 是正确的。
An aspen grove needs to experience fire or some other disturbance regularly, or it will fail to regenerate and spread.
Instead, coniferous trees will invade the aspen grove's borders and increasingly block out sunlight needed by the aspens.取而代之的是,针叶树会侵入白杨树林的边界,并逐渐遮挡白杨所需的阳光。
【instead】取而代之的是,很明显之后跟的那句话是答案
Instead, coniferous trees will invade the aspen grove's borders and increasingly block out sunlight needed by the aspens.
Instead, coniferous trees will invade the aspen grove's borders and increasingly block out sunlight needed by the aspens.
instead 后答案
做这种题目常见的法子就是取反,不过这题压根取反都不用;直接给出答案了
前后找,前面说了个机制:如果fail,那么就说这分泌这个h是照常进行的;A就错了
向后找:instead,很明显的指示词;
Instead, coniferous trees will invade the aspen grove's borders and increasingly block out sunlight needed by the aspens.