虽然约翰对一切都心中有数，但他从不拿癌症话题开玩笑。
Even though John always had a ready answer, he never joked about cancer apparently.
“心中有数”用英语怎么说？
虽然约翰对一切都心中有数，但他从不拿癌症话题开玩笑。
Even though John always had a ready answer, he never joked about cancer apparently.
