chọn đáp án đúng ạ Sputnik 1 was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth (23) ______ on 4th October 1957. It was visible all around the Earth and its radio pulses were detectable. The launch ushered in new political, military, technological (24) ______ scientific developments. Sputnik 1 was launched during the International Geophysical Year from Site No.1/5, in Kazakh SSR. The satellite travelled at about 29,000 kilometers per hour, taking 96.2 minutes to complete each orbit. Tracking and studying Sputnik 1 from Earth provided scientist (25) ______ valuable information, even though the satellite itself wasn’t equipped with sensors. It transmitted on 20.005 and 40.002 MHz, which were monitored by amateur radio operators throughout the world. The signals continued for 21 days until the transmitter batteries (26) ______ out on 26th October 1957. Sputnik burned up on 4th January 1958 (27) ______ reentering Earth’s atmosphere. Question 23: A:orbit B:conduction C:mission D:omission Question 24: A:also B:as C:and D:or Question 25: A:for B:with C:to D:in Question 26: A:ran B:run C:had run D:had ran Question 27: A:because B:while C:until D:since