下列炔烃中,在HgSO4-H2SO4的存在下发生水合反应,能得到醛的是
A. 乙炔
B. 丁-2-炔
C. 丙炔
D. 丁-1-炔
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某烯烃经臭氧化和还原水解后只得到 CH3COCH3, 则该烯烃为
A. (CH3)2C= C(CH3)2
B. (CH3)2C=CH2
CH3CH=CH2
D. (CH3)2C=CHCH3
The size and location of the world's deserts are always changing.Over millions of years,as climateschange and mountains rise,new dry and wet areas appear. But within the last hundred years,desertshave been increasing at frightful speed. This is partly because of natural changes,but men should beresponsible for creating deserts most.
Read the article and match the titles with the paragraphs.
1. I’ve been______toalmostallkindsofpetsformywhole life,butluckilythere arestilla fewIcan live with.A. sensitive B. allergic C. alert D. adaptable2. If I had known how he felt, I would never have let him ______ those children.A. adapt B. adjust C. adopt D. advocate3. Never think success is merely a ______ of luck. Rather, it’s the result of untiring efforts.A. piece B. wee C. stroke D. slight4. Anearthquakehitthecapital,causing______amongthepopulation.A. scare B. panic C. fear D. fright5. Mr. Burns had to quit his position as CEO, after it came to light that his brother was in jail for corruption. Shareholders got scared he might have more skeletons in the ______.A. cabinet B. safe C. wardrobe D. closet6. Inoticedaslight ______ofdisagreementonhisface.A. nodding B. wink C. frown D. complexion7. The parents showed remarkable forbearance toward their ______ and unruly son.A. defiant B. disciplined C. dishonest D. dutiful8. After all the losses, we had to start from ______ and it took times.A. scramble B. scream C. scrape D. scratch9. Amongthehabitswhichchildrenshould_____areslovenliness,rudeness,laziness, lying,stealingandslandering.A. shake B. shrink C. shatter D. shun10. When an earthquake strikes, most people ______ in doorways, or other strong points in their homes.A. cower B. cuddle C. huddle D. curl11. Mydaughterranawayfromhome,Ihaveto______herbackatonce.A. talk B. persuade C. convince D. coax12. Relief agencies are stepping up efforts to provide refugees with food, ______ and medical supplies.A. facilities B. shelter C. residence D. rescue13. Hewilltalktoanyoneand______ outhislifestorytoatotalstranger.A. spill B. confide B. disclose D. reveal14. Seeking to ______ from punishment, he only brought more suffering upon himself.A. avoid B. escape C. flee D. shun15. You'vebeendriftingfromjobtojobwithoutanyreal______.A. commitment B. seriousness C. duty D. passion