A meteorological researcher analyzes weather conditions over the venue of the second China International Import Expo during a rehearsal held in the Shanghai's National Exhibition and Convention Center on Oct 15, 2019. The rehearsal is the last one of its kind for the coming expo. (Photos: VCG)

Crowds enter Shanghai's National Exhibition and Convention Center, simulating visitors for the second China International Import Expo during a rehearsal in Shanghai on Oct 15, 2019. The rehearsal is the last one of its kind for the coming expo.

Medical care personnel in rehearsal at the Shanghai's National Exhibition and Convention Center on Oct 15, 2019 for the second China International Import Expo.

Crowds wait for a security check before entering Shanghai's National Exhibition and Convention Center, simulating visitors for the second China International Import Expo during a rehearsal in Shanghai on Oct 15, 2019.

Crowds wait for a security check before entering Shanghai's National Exhibition and Convention Center, simulating visitors for the second China International Import Expo during a rehearsal in Shanghai.

Crowds wait for a security check before entering the Shanghai's National Exhibition and Convention Center, simulating visitors for the second China International Import Expo during a rehearsal.

Crowds wait for a security check before entering the Shanghai's National Exhibition and Convention Center, simulating visitors for the second China International Import Expo during a rehearsal.

Crowds wait for a security check before entering the Shanghai's National Exhibition and Convention Center, simulating visitors for the second China International Import Expo during a rehearsal.

Crowds pass through the security check before entering Shanghai's National Exhibition and Convention Center, simulating visitors for the second China International Import Expo during a rehearsal.

A security guard monitors the venue for the second China International Import Expo during a rehearsal.