如果这个动作困难，你可以通过抬起脚趾并伸展它们，这样可以抬起内侧足弓才感受这个动作。

If that action is difficult, you can get the flavor of it by raising your toes up and spreading them which will also lift the inner arches.

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捕捉面部表情，并用这些表情来操纵虚拟角色的表情，比捕捉肢体动作困难得多，因为它涉及的动作微小得多，也更加难以捉摸。

Capturing facial expressions and using them to drive the expression of a virtual character is more difficult than motion capture, because the movements involved are much smaller and more subtle.

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婴儿快速而散乱的动作常常使得准确记录反应数量变得困难。

Often the rapid and diffuse movements of the infant make it difficult to get an accurate record of the number of responses.

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