gwd18-17QX，那位大虾给指点一下吧

Rivaling the pyramids of Egypt or even the ancient cities of the Maya as an achievement, the army of terra-cotta warriors created to protect Qin Shi Huang, China’s first emperor, in his afterlife is more than 2,000 years old and took 700,000 artisans more than 36 years to complete them.

it多余

GMAT语法中，在不引起歧义，不产生语法错误的情况下，能简洁就简洁！

可以按抽取主谓宾的方法:

Simply, it is Who does what.

In passive voice, it is what is been done, for example, the work took a week to complete. Not "the work took a week to complete it."

In this sentence, it is the army took more than 36 years to complete. Not " the army took more than 36 years to complete it."

正如楼上所说，这个it是多余的。

234. The physical structure of the human eye
enables it to sense light of wavelengths up to 0.0005 millimeters;
            infrared radiation, however, is invisible because its
wavelength--0.1 millimeters--is too long to be registered by the eye.

(A)  infrared radiation, however, is invisible because its wavelength--0.1
millimeters--is too long to be registered by the eye

(B)   however, the wavelength of infrared radia­tion--0.1
millimeters--is too long to be registered by the eye making it invisible

(C)  infrared radiation, however, is invisible because its wavelength--0.1
millimeters--is too long for the eye to register it

(D)  however, because the wavelength of infrared radiation is 0.1
millimeters, it is too long for the eye to register and thus invisible

(E)   however, infrared radiation has a wavelength of 0.1 millimeters
that is too long for the eye to register, thus making it invisible

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