以下哪个可能是红外发射管? <img src="http://static.cnmooc.org/repositry/umeditor/i/1809/21/3ae9e2e59549454a9b070ff118168864.jpg" />|<img src="http://static.cnmooc.org/repositry/umeditor/i/1809/21/394f173e66bd4376b5fcef9c399105b6.jpg" />|<img src="http://static.cnmooc.org/repositry/umeditor/i/1809/21/502a44e8f77f40078a8d9519a1e6923a.jpg" />|<img src="http://static.cnmooc.org/repositry/umeditor/i/1809/21/dd21e7635f994ad1a0134d620715fb1f.jpg" />

Washington Irving’s first book appeared in 1809, entitled ______.

中国大学MOOC: Songs of Innocence, published in 1809, is a lovely volume of poems. The poems praise _______.

In what year was the Jami-Ul-Alfar Mosque completed? A: 1909 B: 1809 C: 1908 D: 1890

【单选题】73÷(26+38)的算式用文字表达是() A. 73 除以26加上38 B. 73 除以26的商加上38 C. 73 除以26加上38的和 D. 26 加上38的和除以73

第一架钢琴是（）年发明的 A: 1709 B: 1809 C: 1909 D: 1609

第一架钢琴是（）年制成的。 A: 1809 B: 1609 C: 1709 D: 1790

宝典73

_____entered into force in1983. A: A revised version of Annex I of MARPOL 73/78 B: A revised version of Annex II of MARPOL 73/78 C: A revised versions of Annex I and Annex II of MARPOL 73/78 D: MARPOL 73/78

世界上第一架钢琴是什么时候产生的（） A: 1709 B: 1800 C: 1719 D: 1809