Here are 6 pairs of word with ш and щ in different positions:

- вешать (to hang) - вещать (to broadcast);

- шалаш (a hut) - щадить (to have a merci);

- уши (ears) - ущелье (canyon);

- шум (noise) - щука (a pike);

- шипеть (to hiss) - щипать (to pinch)

- шелк (silk) - щелкать (to click).