Thanks for your reply. I will try to search the 凹凸小腳踏 in Toys "R"Us.
These days, we try to let him walk by himself, didn't hold his hands. I can see him walk with both feet on the floor more often. However, it leads to another problem.... he walks too quick & too far... he looks back, laughs with me... seems want me to trace him... very dangerous....
Anyway, thanks for your kindness.
One more surprise, i saw him jump this Monday & Tuesday when he was playing & singing !