Much of what we see in the universe... starts out as imaginary. Often you must imagine something before you can come to terms with it. — Clifford D. simak.
我们在宇宙中的大部分所见都是从想象开始的。经常是在你真正看到这个事物之前，你已经把它想象出来了。
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An expression that is the sum of a real number and a vector and that contains four terms, one real and three imaginary.