An artist is seen with his artworks at Green Path, a hub of open-air art shows, in Colombo, capital of Sri Lanka, on July 4, 2020. Open-air art shows at Green Path disappeared temporarily due to a nationwide curfew imposed by the Sri Lankan government to prevent the spread of COVID-19 since March 20. After the curfew was lifted on June 28, artists gradually returned here to display their artworks. (PHOTO / XINHUA)

Professor Albert Bosch from the Faculty of Biology of the University of Barcelona works in the office. He confirmed on June 29 that a study he had coordinated detected the presence of the novel coronavirus in waste water samples collected in Barcelona on March 12, 2019. (PHOTO / XINHUA)

A woman pays attention to the situation at the explosion site in Teheran, June 30, 2020. At least 19 people were killed in an explosion at a clinic in the northern district of Iran's capital Tehran on Tuesday, said Jalal Maleki, spokesman for the Firefighting Organization of Tehran. (PHOTO / XINHUA)

People visit the Sagrada Familia basilica on the day of its reopening in Barcelona, Spain on July 4, 2020. One of Spain's most famous landmarks, Sagrada Familia opened its doors to visitors last Saturday for the first time since Spain was placed under lockdown on March 14 due to the coronavirus pandemic. (PHOTO / XINHUA)

Edouard Philippe (left) and Jean Castex (right) attend the handover ceremony in the courtyard of the Hotel Matignon in Paris, Franc, on July 3, 2020. Jean Castex, a 55-year-old top civil servant not known to the French general public, was appointed new prime minister by President Emmanuel Macron to replace Edouard Philippe, the French presidential palace announced last Friday. (PHOTO / XINHUA)

People visit the Flea Market in Frankfurt, Germany on July 4, 2020. The market, which trades secondhand goods, reopened here last Saturday with strict COVID-19 prevention measures. (PHOTO / XINHUA)

Students wearing masks and shields participate in a college entrance exam in Sale, Morocco on July 3, 2020. (PHOTO / XINHUA)

A formation of planes flies over Washington DC area during an air show to celebrate US Independence Day on July 4, 2020. (PHOTO / XINHUA)

People ski at Whakapapa ski field in New Zealand's North Island on July 4, 2020. The ski field opened a small portion at a lower elevation to the public last Friday. (PHOTO / XINHUA)

A man shows desert locusts he caught in Sanaa, Yemen on July 3, 2020. Desert locusts swarmed through the Yemeni Houthi-held capital Sanaa last Friday, invading crops and leaving farmers of the war-torn country in despair. (PHOTO / XINHUA)

The audience watches Beethoven's Fidelio in separate boxes during the Film Festival at Vienna's Rathausplatz, Austria on July 4, 2020. This year's Film Festival at Vienna's Rathausplatz opened last Saturday. (PHOTO / XINHUA)

Workers set up a care centre converted from an indoor stadium as the numbers of COVID-19 cases rise in New Delhi, India, on June 30, 2020. (PHOTO / XINHUA)

A health worker takes a throat swab sample of a passerby for COVID-19 testing in Kigali, capital of Rwanda, July 2, 2020. Rwanda's Ministry of Health on Thursday launched a COVID-19 street testing survey in Kigali to probe the COVID-19 situation in the city. (PHOTO / XINHUA)

Rescuers carry the body of a victim after the landslides at a jade mining site in Hpakant, Kachin State, Myanmar on July 2, 2020. (PHOTO / XINHUA)

A relative makes a phone call near a fireworks factory where an explosion happened in Sakarya province, Turkey, July 3, 2020. Turkish ministers on Friday said the death toll in an explosion at a fireworks factory in Turkey's northwestern province of Sakarya rose to four and the number of wounded people to 108. (PHOTO / XINHUA)