题目6A. <img src="https://tihai-oss-cloud.itihey.com/img/c63481b535c76dca183d5652fae1d1aa.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/243c2ef66f8e5a38e97c7e57c77dc395.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/e25c78704b77cdf53ab165e448887f77.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/2fec3f027ebc4f786ee77c3798c23952.png">