No, "drinking" is a gerund, a verbal noun, not a present tense, in that case.
How can we know if it is child(singular) or children(plural)? There was a similar case in this lesson, where "indians" was "người ấn độ" instead of "những người ấn độ"
Can someone please clear my doubt? :)
"Đứa trẻ" = child "Những đứa trẻ" = children. Hope you enjoy with that.