I have black _______.   

方程$\sqrt{1-x^2}=kx+2$有唯一解，则实数k的取值范围是(　　)

2014年3月24日，******出席了在荷兰海牙举行的第三届核安全峰会。我国打破帝国主义核垄断的事件是（  ）

下列图示实验操作中，正确的是（   ）

阅读下列材料，从A、B、C三个选项中，选出最佳选项回答问题或完成句子.
    Miss Miller, The English Teacher wants to know about her students. She asks them some questions. The next are some of the students' answers(回答):

First name: Grace       Last name: Smith           Class: 1 School things: 2dictionaries, 4 pencil boxes, 8 notebooks

First name: Tony        Last name: Green          Class: 2 Things and positions: Watch: on the table        Volleyballs: under the desk Keys: in the schoolbag      Computer games: on the sofa

First name: Alice          Last name: Smith         Class: 3 Likes: apples, carrots, chicken, strawberries Doesn't like: bananas, salad, ice-cream