化合物[img=58x86]1803351c5ee5bc1.jpg[/img]在光照下发生周环反应的产物是
A: [img=99x81]1803351c6a7ccca.jpg[/img]
B: [img=97x71]1803351c77023a4.jpg[/img]
C: [img=101x90]1803351c82d8882.jpg[/img]
D: [img=97x81]1803351c8dbb43b.jpg[/img]
A: [img=99x81]1803351c6a7ccca.jpg[/img]
B: [img=97x71]1803351c77023a4.jpg[/img]
C: [img=101x90]1803351c82d8882.jpg[/img]
D: [img=97x81]1803351c8dbb43b.jpg[/img]
举一反三
- 获取页面中所有jpg格式的图片，以下写法正确的是（）。 A: $（"img[src$=jpg]"） B: $（"img[src^=jpg]"） C: $（"img[src=jpg]"） D: $（"img[src*=jpg]"）
- 设随机变量X的概率密度[img=190x71]17de89917dd344e.png[/img]，则[img=87x47]17de89918b2d7b8.png[/img]的值为 A: 5 B: 3 C: 81/16 D: 4
- Which of the following propositions is false,set A = {x,x is an integer and[img=60x23]1803a1c6eebb7a3.png[/img]} ? ( ) A: [img=113x25]1803a1c6f77ce06.png[/img] B: [img=139x25]1803a1c7001fe79.png[/img] C: [img=51x22]1803a1c70863f61.png[/img] D: {x|x is an integer and |x| 4}[img=33x22]1803a1c711a7c63.png[/img]
- Which of the following propositions is false,set A = {x,x is an integer and [img=60x23]1803a1c503ffa04.png[/img]} ? ( ) A: [img=113x25]1803a1c50cc3162.png[/img] B: [img=139x25]1803a1c514e60ea.png[/img] C: [img=51x22]1803a1c51dd52ef.png[/img] D: {x|x is an integer and |x| <4} [img=33x22]1803a1c525cf1bd.png[/img]
- 下列4个集合中是空集的是（） A: ｛x|[img=18x22]1802f060e2f728f.png[/img]+1=0｝ B: ｛x|[img=18x22]1802f060e2f728f.png[/img]<-x｝ C: ｛x|[img=18x22]1802f060e2f728f.png[/img]=0｝ D: ｛x|[img=18x22]1802f060e2f728f.png[/img]-1=0｝