【单选题】There is____ "s" in the word "us".
【单选题】There is _______ "s" in the word "six" and _______ "s" is the first letter of the word.
【简答题】生物氧化是在 进行的 过程,反应条件 。
【单选题】There is ____ "u" and ____"s" in the word "use".
【判断题】生物质气化过程是在充足的空气或氧气条件下进行的热化学反应。
【单选题】There is _____ "u" and ____ "s" in ___ word "use".