帮我翻译一下：theobromine was nearly a third more effective in stopping coughs than codeine

可可碱的止咳效果要比可待因的止咳效果高近三分之一。

1楼的看好是 more effective

可可碱在镇咳方面只有可待因三分之一的功效.

theobromine was nearly a third more effective in stopping coughs than codeine.

"可可碱"比"可待因"的止咳效果要强近1/3。

可是近三分之一的可待因更有效地阻止咳嗽