单选题 1.   The grandparents couldn't help to smile when they saw the gold medal their grandson had got at the Olympic Games.
【正确答案】 B
【答案解析】 应改为smiling。本题考查非谓语动词。can't help(to)do sth.意为“不能帮助做某事”；can't/couldn't help doing sth. 意为“情不自禁做某事”。根据句意可知，此处应用smiling。
   当看到孙子在奥运会上取得的金牌时，爷爷奶奶情不自禁地笑了。