tā / suī / rán / nǔ / lì / bǎo / chí / zhèn / dìng / hái / shi / xǐ / xíng / yú / sè / de / xiào / le / qǐ / lái

他虽然努力保持镇定，还是喜形于色地笑了起来。

Although he tried to remain calm, he still broke into a delighted smile.