题干

对化学知识的归纳和整理,有助于我们深入理解并掌握化学知识,下列有关归纳正确的是(  )


A:淀粉遇到碘水呈现蓝色,所以与碘水作用呈现蓝色的物质中一定含有淀粉

B:碱溶液都能使酚酞试液变红,所以能使酚酞液变红的溶液一定是碱溶液

C:碳酸盐都能与稀硫酸反应放出气体,所以能与稀硫酸反应放出气体的物质一定是碳酸盐

D:二氧化碳能使燃着的木条熄灭,所以能使燃着的木条熄灭的气体一定是二氧化碳

上一题 下一题 0.0难度 选择题 更新时间:2018-10-04 04:47:37

答案(点此获取答案解析)

A

同类题5

阅读理解

    Here are Important Travel Notices from United Airlines, March 20, 2016 7:12 AM. Information is updated as it is received.

    ⒈Travel and the Zika virus

    If you have a ticket for travel to a country affected by the Zika virus(as listed on the CDC website) and have concerns, please contact the United Customer Contact Center with any questions or changes to your reservation. Customers advised to avoid the affected regions based on CDC guidance may change their destination or travel date without a fee or may choose to receive a refund(退款) if their tickets were booked before February 29,2016. The new travel date must be within the validity of the ticket. Additional charges may apply if there is a difference in fare for the new travel route.

    ⒉Longer lines at security checkpoints

    Procedural changes at TSA checkpoints throughout the United States may result in longer lines at security checkpoints. Please plan accordingly and allow for extra time at the airport. The TSA advises arriving at the airport two hours before your flight for US travel and three hours before for international travel. To save time at security, we encourage you to visit www.tsa.gov.com and apply for TSA pre-check.

    ⒊Notice for flight departing the European Union, Norway and Switzerland

EU Regulation 261/2004 requires airlines to provide the following notice: If you are not allowed to board or if your flight is canceled or delayed for at least two hours, ask at the check-in counter or boarding gate for the form, stating your rights, particularly about compensation assistance.