else if statement bash syntax

#!/bin/bash
 
read -p "Enter your marks: " marks
 
if [ $marks -ge 80 ]
then
    echo "Very Good"
 
elif [ $marks -ge 50 ]
then
    echo "Good"
 
elif [ $marks -ge 33 ]
then
    echo "Just Satisfactory"
else
    echo "Not OK"
fi

if [[ TEST-COMMAND ]]
then
  STATEMENTS1
else
  STATEMENTS2
fi

if [ "$animal" == "penguin" ]; then
  echo "Hmmmmmm fish... Tux happy!"
elif [ "$animal" == "dolphin" ]; then
  echo "Pweetpeettreetppeterdepweet!"
else
  echo "*prrrrrrrt*"
fi

if TEST-COMMANDS; then
  CONSEQUENT-COMMANDS;
elif MORE-TEST-COMMANDS; then
  MORE-CONSEQUENT-COMMANDS;
else
  ALTERNATE-CONSEQUENT-COMMANDS;
fi