题目

尿素是一种重要的农业肥料，但若不经细菌的分解，就不能更好地被植物利用。下列有关土壤中尿素分解菌的分离和培养的叙述，正确的是（ ） A．培养基中加入尿素作为唯一碳源，该培养基是鉴别培养基       B．测定土壤中分解尿素的细菌数量和测定土壤中其他细菌的数量可采用相同的稀释度    C．细菌合成的脲酶能将尿素分解成氨，氨会使培养基的碱性增强，pH升高      D．利用稀释涂布平板法可以直接完成土壤中分解尿素的细菌的分Saturday，March 25thThis morning my family 1. ( 决定) to climb the mountain for exercise. We walked up to the 2._（顶部）and enjoyed beautiful flowers along the way. It was so 3. (精彩的)! 4. (不过), it began to rain before we got back home. We didn’t take 5. (雨伞), so we were all 6. (湿的).We all need to exercise. It makes our 7. (心智) and bodies healthier，and we will feel better about _8._ (我们自己). My parents said that it was best to exercise two or three times a week and twenty minutes each time was 9. (足够的).Exercise is also fun, we can spend time with our friends and family as we play sports 10. (在一起). So start exercising before it’s too late!