We substituted a red ball for blue to see if the baby would notice.
We substituted a red ball for blue to see if the baby would notice.
我们用红皮球换下了蓝皮球，看这婴儿会不会发觉。
We substituted a red ball for blue to see if the baby would notice.
我们用红皮球换下了蓝皮球，看这婴儿会不会发觉。