Manchester United’s scoring woes were on display again as the English powerhouse labored to a 0-0 draw at AZ Alkmaar in another poor display in the Europa League on Thursday. Arsenal had no such problems, with teenage forward Gabriel Martinelli scoring twice in a 4-0 win over Standard Liege. United has not scored more than one goal in any of its last eight matches in all competitions and the latest setback will only increase the pressure on manager Ole Gunnar Solskjaer to get the team’s attack firing again. Arsenal manager Unai Emery may have unearthed a real gem in Martinelli, though, as the Brazilian has now scored four goals in two starts for the club. Against Liege, he netted twice within two minutes early in the first half and set up another goal for Dani Ceballos in the second. In Luxembourg, the Group A game between Dudelange and Azerbaijani club Qarabag had to be suspended in the first half for after a drone flew over the pitch carrying what looked an Armenian flag. The drone incensed Qarabag players, who tried to hit it with the ball. Azerbaijan and Armenia are in a territorial dispute over the Nagorno-Karabakh region. Play was…