Sweden's Charlotte Kalla (C) and Norway's Marit Bjoergen (L) compete during the Ladies' 7.5km + 7.5km Skiathlon of Cross-Country Skiing at the 2018 PyeongChang Winter Olympic Games at the Alpensia Cross-Country Skiing Centre in PyeongChang, South Korea, on Feb. 10, 2018. (Xinhua/Bai Xuefei)