中国联通

中 = 丨 + 口 : Mnemonic symbol: a dart board, because you always try to hit the center.

Julian Giant Squid (zhu-) is throwing dinosaur bones (丨) as darts on a dart board in front of the engine ((e)ng1). To make it a bit more difficult he's throwing mandarins (口) into the air as well and skewers them up right in the center (中 is a mandarin skewered on a dinosaur bone) in mid flight with the dinosaur bones. He's still able to consistently hit the center (中) of the dart board.

国 = 囗 + 玉 : Mnemonic symbol: a nation's flag. Let's say the Chinese flag.

In the observatory's kitchen (o2) Gitta Giraffe (gu) is practising her ballet performance. She got a whole crate (囗) full of jade bracelets (玉) and flags (国) and fixed one flag to each jade bracelet. This makes a perfect combination for throwing the ring with the flag waving behind it and catching the ring again after a few pirouettes.

联 = 关 + 耳 : Li Qingzhao (li) invented a machine able to combine (联) her hair into braids, and she is trying it out for the first time in the anthill's kitchen (an2). Just as the machine starts Li Qingzhao realizes it is going to combine both of her ears (耳) into one braid she quickly hits the machine's off button (关).

通 = 甬 + 辶 : In front of the engine a pile of yongzhong bells were blocking the way. Tommy Turtle attended to the matter and cleared the way. He lined the bells up to two lines, put on his gladiator sandals and now marches right through this path screened by walls on two sides like a roman general.