他的才智和头脑的敏锐从未被受到怀疑。

His intellect and mental agility have never been in doubt.

《柯林斯英汉双解大词典》

由于收容所缺乏足够的空间和资金来看护那些未被认领的猫狗，很多人怀疑更多的动物已被实行安乐死。

There is some concern that even more are being put to sleep now, because shelters do not have the space or money to keep alive animals that have not been adopted.

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对这种差异的怀疑存在已久，但是从未被证实过。

Such differences had long been suspected but never proven.

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