19. At the tide ____ from the shore, we are able to look for shells.
A. preceded B. proceeded C. acceded D. receded
<precede>
precede 在…之前，领先于，优先
</precede>
<recede>
recede 撤退
concede 妥协，让步
concession 让步
compromise 妥协，让步
</recede>
